Instruction Manual Model 388 (RI-212) Ranarex Gravitometer Revision D - May 2010 Filename: RI-212D1.doc ________________ S/N ________________
CHANDLER E N G I N E E R I N G P.O. Box 470710 Tulsa, Oklahoma 74147-0710 U.S.A. Telephone: 918-250-7200 FAX: 918-459-7199
Copyright © 1999, 1999, by Chandler Engineering Company, LLC P.O. Box 470710 Tulsa, Oklahoma 74147 All rights reserved. Reproduction or use of contents in any manner is prohibited without express permission permission from Chandler Engineering Company, LLC. While every precaution has been taken in the preparation of this manual, the publisher assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein.
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ii
TABLE OF CONTENTS
SPECIFICATIONS. SPECIFICATIONS........ ............... ................ ............... ............... ................ ............... ......... .. III PORTABLE TYPE GRAVITOMETER ........................................... GENERAL ..............................................................
III III
SECTION 1 - GENERAL INFORMTION..... INFORMTION............. ............... ............... ................ ............ .... 1-1 1.1 RANAREX GAS GRAVITOMETERS ................ ....................... ............... ................ ........ 1-1 ....................... ................ ............... .............. ....... 1-1 1.2 THEORY OF OPERATION ............... 1.3 CONDITIONING THE GAS AND AIR SAMPLES ............... ....................... ............. ..... 1-2 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6
........................................... ............... Dry Reference Air ............................ .................................................... ........................ Pressure ............................ ................................................. ........................ Temperature ......................... ............................................ ................... Moisture Content ......................... Filtering ........................... ................................................... ........................ Sampling Systems ......................... ............................................ ...................
1-2 1-2 1-3 1-3 1-3 1-3
SECTION 2 - INSTALLATION.......... INSTALLATION.................. ............... ............... ............... ............. ...... 2-1 SECTION 3 - OPERATION............. OPERATION..................... ............... ............... ............... ............. ...... 3-1 ....................... ............... ............... ................ ............... ......... .. 3-1 3.1 PROCEDURE ............... 3.1.1 3.1.2 3.1.3 3.1.4
............................................. ................... Zero Adjustment .......................... Response Time ............................ ............................................... ................... .................................... .......... Over-Pressure Protection .......................... Purging to 1.000 After Measuring a Gas ......................
3-1 3-2 3-2 3- 2 3-2
SECTION 4 - MAINTENANCE AND SERVICING.......... SERVICING................. ............... ................ ........ 4-1 4.1 4.2 4.3 4.4
....................... ............... ................ ............... .............. ....... LUBRICATION ................ SELECTOR VALVE ............... ....................... ............... ............... ................ ............ .... ...................... ............... ................ ............... .............. ....... POINTER LOCK ............... CARE OF THE CONNECTING TAPE ............... ....................... ............... .............. .......
4-1 4-1 4-1 4-2
........................................... ............... 4-2 4.4.1 Tracking the Tape ............................ ........................................... ............... 4-2 4.4.2 Cleaning the Tape ............................ .......................................... ............... 4-2 4.4.3 Replacing the Tape ...........................
4.5 4.6 4.7 4.8
DRIVE BELT TENSION ............... ....................... ............... ............... ................ ........ ....................... ............... ............... ............... ............. ...... IDLER BEARING ............... GRAVITOMETER DISASSEMBLY PROCEDURE ................ ....................... .............. ....... ...................... ............... ................ ............... ......... .. IMPELLER BEARINGS ...............
4-2 4-2 4-3 4-3
........................................ ............... 4-4 4.8.1 Impeller Disassembly ......................... ........................................... ............... 4-4 4.8.2 Impeller Assembly ............................
....................... ................ ............... ............... ........... ... 4-4 4.9 TROUBLESHOOTING ...............
SECTION 5 - CALIBRATION........... CALIBRATION................... ............... ............... ............... ............. ...... 5-1 5.1 CALIBRATION PULLEY ............... ....................... ............... ............... ................ ........ 5-1 SECTION 6 - PARTS LISTS............ LISTS.................... ............... ............... ................ ............ .... 6-2
LIST OF FIGURES
Fig. Fig. Fig. Fig.
ii
1 2 3 4
– – –
RANAREX Measuring System............................................. Outline and Mounting Dimensions...................................... Location of Connections and Controls................................. Operating Instruction Plate..........................................
1-1 2-1 2-2 3-1
SPECIFICATIONS{tc \l1 "SPECIFICATIONS}
PORTABLE TYPE GRAVITOMETER{tc \l2 "PORTABLE TYPE GRAVITOMETER} Case: Portable with carrying handle Size: 132"W x 132"H x 10f"D, excluding handle and gas hose connections Weight: Approximately 38 lb
Readings: Indicating dial
Drive Motor: 115 volt, " 10% 50 or 60 Hz, single-phase Permanent split-capacitor (no arcing during Start, Run or Stop) Explosion-proof motor not available
Accuracy: Within 0.5% of actual value at any reading within range
Portable Gravitometers : Dual-range: 0.52-1.03 and 0.97-1.90
GENERAL{tc \l2 "GENERAL} Materials : Case and Chassis: Aluminum Impellers, Impulse Wheels: Molded phenolic Drive: Stainless steel shafts; sealed ball bearings Pivots: Stainless steel shafts in jewels Internal trim: Aluminum and stainless steel
Ambient Temperature Rating : Saturated gas and air: 40 to 120 EF2 (4E - 50EC). Normal gas and dry air: 0 to 130 EF2 (-18E - 54EC).
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SECTION 1 GENERAL INFORMATION
1.1 RANAREX GAS GRAVITOMETERS{tc \l2 "1.1 RANAREX GAS GRAVITOMETERS} RANAREX gravitometers measure the relative density (specific gravity) of gases as compared to air at standard temperature and pressure (STP). For all gases there is a definite relation between the composition of the gas mixture and its relative density. The instrument is calibrated over two ranges to indicate relative density. RANAREX gravitometers excel over more complex and costly analyzers in total performance, including simplicity, fast response, accuracy, sensitivity, ruggedness and lowest long-term cost.
1.2 THEORY OF OPERATION{tc \l2 "1.2 THEORY OF OPERATION} The RANAREX gravitometer uses dynamic forces to measure the relative density of a gas. The operating principle is described below. The instrument contains two cylindrical gas-tight measuring chambers, each having separate inlet and outlet connections. Each chamber contains an impeller and an impulse wheel. These wheels oppose each other on separate shafts in a way that resembles an automotive fluid coupling or torque converter. An electric motor and drive belt rotate both impellers at the same speed. The impellers draw the sample gas and dry reference air into their respective chambers. The torques created on the impulse wheels are proportional to the densities of the gas and of the reference air. The impulse wheel shafts are coupled using a cam and flexible tape in a way that causes the torques to balance. The ratio of the sample impulse wheel torque to the reference impulse wheel torque represents the relative density of the gas. A mechanism and graduated dial are used to indicate the relative density.
Figure 1 illustrates the measuring system for two operating conditions. The left view shows the position of the cam and reference wheel when the reference gas is admitted into both chambers. In this case, the impeller wheel torques will be equal. As a result of this condition, and the linear profile of the cam, the graduated dial is calibrated to indicate 1.000. The right view of Figure 1 shows the position of the cam and reference wheel when an unknown gas is admitted to the upper chamber and reference air is admitted into the lower chamber. The lighter gas (in the upper chamber) creates a smaller torque than Fig. 1 – RANAREX Measuring System the air in the lower chamber. As a result of this condition, the cam will rotate until the cam radii allows the opposing torques to balance. The cam rotation is calibrated to indicate the ratio of the torques, or relative density. To measure relative densities above 1.000, the unknown gas is admitted to the lower chamber and the dry reference air is admitted to the upper chamber. The principle of operation is the same. The graduated dial has two scales. The
1-1
GENERAL INFORMATION
inner scale is used for relative densities below 1.000. The outer scale is used for relative densities above 1.000. Due to the nature of the design, the pressures and temperatures of the gas and reference air are equalized. Any changes in pressure, temperature, and motor speed affect both torques equally. Since the torques produce opposing forces the effects of varying pressure, temperature and motor speed are canceled. An air drier is built into the gravitometer to dry incoming ambient air for use as the reference gas. The gravitometer is equipped with a selector valve that is used to direct sample gas and dry reference air to the correct chambers. The three positions are used for checking the instrument ZERO, for measuring gas relative densities below 1.000, or for measuring gas relative densities above 1.000. The motor is designed for operation on 115 VAC " 10%, 60Hz. When the gravitometer is to be used in an area where AC power is not available, a DC AC invertor may be used to convert the DC voltage supplied by an automobile alternator or other DC source to the correct AC voltage.
1.3 CONDITIONING THE GAS AND AIR SAMPLES{tc \l2 "1.3 CONDITIONING THE GAS AND AIR SAMPLES} To assure accuracy, the gas sample and the reference air must be measured at the same temperature, atmospheric pressure and humidity content. The sampling system must condition the gas and air to meet these requirements. When these conditions are met, the analyzer and sampling system as a unit will be self-compensating for all variations except the analysis and relative density of the gas. The RANAREX gravitometer measures relative density in accordance with the definition: "The ratio of the density of the gas, under the observed conditions of pressure and temperature to the density of dry air at the same pressure and temperature." To provide the basis for accurate measurements a sampling system must satisfy the following conditions:
1.3.1 Dry Reference Air{tc \l3 "1.3.1 Dry Reference Air} Provided by the built-in air drier. The drier uses silica gel as the desiccant and is easily replaced when the silica gel becomes exhausted. NOTE: The silica gel desiccant is normally blue in color. The desiccant must be replaced when the color has changed to pink.
1.3.2 Pressure{tc \l3 "1.3.2 Pressure} The gas sampling system must reduce the gas to barometric pressure to equal the pressure of the reference air. The correct gas pressure corresponds to a sample flow rate of 10-15 scfh for the portable RANAREX gravitometer. The flow rate is measured by a rotameter. As an operating convenience, the flow scale is graduated in relative density units. The operator can adjust the needle valve so that the flowmeter reads the approximate relative density of the gas. For gas pressures above 20 psig, a suitable pressure reducing regulator must precede the rotameter.
1-2
GENERAL INFORMATION
NOTE: The flowmeter can be used with inlet pressures up to 20 Psig. When the sample pressure is above 20 Psig it must be reduced using an external pressure regulator.
1.3.3 Temperature{tc \l3 "1.3.3 Temperature} The reference air is admitted to the gravitometer at the ambient temperature of the instrument. For the gas and air to be measured at the same temperature, the gas must be heated or cooled to ambient temperature. This is important if the gas pressure has been reduced more than 100 Psig, or if the gas flows through a temperature zone more than 10 EF (12EC) different from the ambient temperature of the gravitometer. If the sample gas temperature must be adjusted, the gas may be passed through a coiled 10 ft. (30m) section of metal tubing before entering the gravitometer.
1.3.4 Moisture Content{tc \l3 "1.3.4 Moisture Content} Gases that are "wet" (dew point above 50 EF, 10EC) must be measured against humidified air. Gases that are "dry" (dew point below 50EF, 10EC) or gases which would be dissolved by a humidifier, such as NH 3, or gases which are corrosive when moist, such as SO 2, must be measured against dry air. Dry instrument air may be reduced to barometric pressure and used as reference air. If instrument air is not available, ambient air can be dried and, when specified, the gravitometer will be equipped with an integral air drier.
1.3.5 Filtering{tc \l3 "1.3.5 Filtering} A commercial filter (25 micron) must be used ahead of the regulator and flowmeter to protect the instrument. Other precautions must be used to prevent liquids from entering the instrument. A Balston filter (or equivalent) may be required. NOTE: RANAREX instruments do not include the gas filter, pressure reducing regulator or sample hose because most users have individual preferences for these items and maintain their own stock.
1.3.6 Sampling Systems{tc \l3 "1.3.6 Sampling Systems} Components for conditioning the gas and reference air may be furnished by the purchaser. However, as a convenience and to assure correct selection, it is recommended that they be purchased with the RANAREX gravitometer.
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SECTION 2 INSTALLATION
Fig. 2 – Outline and Mounting Dimensions
1.
Check all accessories. A.
All RANAREX gravitometers include: 1 1 1 1
Electric cord, 6 ft. of 18 gauge cable with male and female plugs 1-1/2 lb. can indicating silica gel Filling funnel Instruction Manual
B. When the RANAREX gravitometer is operated from a 12 volt DC battery, the following is also furnished, unless excluded by Purchaser: 1 2 1
RANAREX Invertor Battery Cables, 16 ft. of 12 gauge wire with battery clips Inverter Instruction Manual (found in Reference Material section of Gravitometer manual)
2. Select the location for the gravitometer. The instrument should not be near hot or cold objects. Allow at least 5" clearance on the left side and 3" on the right side for making connections and normal operating functions. If the instrument is to be permanently mounted in one location, it should be secured with four 1/4-20 machine screws. These screws are used with the holes in the gravitometer base. See Figure 2 for mounting dimensions of the gravitometer and the location of the mounting holes. See Figure 3 for location of connections and external controls. 3. Install the power inverter. the inverter.
Read the instructions that are packed with
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WARNING: Do not operate RANAREX without first reading the Operating Instructions.
4.
Fill the air drier.
The air drier must be removed from the upper left
Fig. 3 – Location of Connections and Controls
side of the instrument by loosening the two fasteners. Remove the plastic drier assembly from the gravitometer far enough until the rubber tube can be removed from the elbow at the rear of the drier. Remove the rubber plug on the front of the drier by lifting the lever at the center of the plug (but do not turn the lever). Hold the drier horizontal with the front face up and pour silica gel using the funnel into the spout. Tap or shake the drier vigorously and continue to fill the drier to the base of the spout. Replace the rubber plug, attach the rubber tube on the elbow at the rear of the drier, install the drier into the gravitometer. NOTE: If the drier assembly is damaged, the entire assembly must be replaced.
The moisture capacity of the silica gel will vary according to the atmospheric humidity and it must be inspected at regular intervals. When the upper half of the narrow compartment shows a change from deep blue color to gray-pink color, the silica gel must be replaced. Active silica gel has a deep blue color and must be kept in a tightly closed container. Expended silica gel has a light grayish-pink color. The silica gel may be reactivated and used over and over again. To reactive, heat the silica gel in an open container to approximately 250 EF until the dark blue color returns, then store in a tightly closed container. Additional silica gel may be obtained from Chandler Engineering as Part Number 300-00259.
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5. Attach the outlet hoses. If the gravitometer is operated in a confined space, such as inside a vehicle, the gas sample must be discharged outside the vehicle. This will prevent contaminating the operating space with noxious or hazardous gas and air mixtures. If measuring only gas below 1.000 relative density, attach a hose to the port LIGHT GAS OUTLET on upper right side of gravitometer case. If measuring gases above 1.000 relative density, attach a hose to the port HEAVY GAS OUTLET . These hoses must remain attached when checking the instrument "zero point". 6. Gas filter. If the gas contains suspended particles larger than 25 microns, or if the gas is "wet", filtering is required. If a commercial filter is not available, a suitable moisture trap may be made from 1" (2.54cm) pipe 15" (38cm) long mounted vertically. Cap both ends and install a drain valve in the bottom cap. Install an inlet connection from the gas line 2" (5cm) from the bottom and place the outlet to the gravitometer 2" (5cm) from top. Fill the pipe loosely with commercial No. 0 steel wool. Drain the trap frequently to keep the steel wool free from condensate. 7. Gas temperature. If the gas sample is at a pressure above 100 Psig, or if the sample flows through a temperature zone more than 10 EF (-12EC) different from the ambient temperature of the gravitometer, sample temperature adjustment is required. Install a section of 3/8" (1cm) metal tube 10 ft (3m) long, and locate it near the gravitometer case. The tube may be coiled or bent to suit the space available. The tube will serve as a heat exchanger to heat or cool the sample gas. 8. Make the gas sample connection. Attach a pressure reducing regulator to the sample tap and route the sample line to the gravitometer. The sample line must be capable of delivering 12 SCFH gas, free of condensed liquids, at a pressure not exceeding 15 Psig. It is recommended to use proper sample probes and sampling techniques as defined in ASTM, GPA, and API standards.
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SECTION 3 OPERATION
CAUTION: This type RANAREX Gravitometer is provided with a Pointer Lock (Figure 3), which must be locked at all times when the drive motor is not operating. The function of the lock is to exert tension on the flexible tape, which connects the cam and reference wheel (Figure 1). This tension maintains correct "tracking" of the tape when the instrument is stopped. The user is cautioned to leave the lock applied until after the drive motor has been started and to apply the lock before shutting off the motor, to avoid operating inconvenience and prevent damage to the instrument.
The "LOCK" position of the pointer is at the upper right corner of the scale, near the 0.970-1.030 graduations. The position of the locking mechanism is shown by the arrow of the knob and the legends on the gravitometer front cover. To check if the pointer is locked, turn the knob to "UNLOCK" and observe if the pointer drifts downward, then turn the knob to the "LOCK" position and observe if the pointer snaps into original position.
3.1 PROCEDURE{tc \l2 "3.1 PROCEDURE} The correct procedure for operating the RANAREX gravitometer is described on the instruction plate located over the center of the indicating scale and reproduced as Figure 4 of this section. It is recommended that the user observe the sequence of steps as listed. In this way, maximum accuracy will be achieved. The following helpful:
comments
are
also
3.1.1 Zero Adjustment{tc \l3 "3.1.1 Zero Adjustment} : The zero adjustment screw must be turned in the direction opposite to the correction required in the pointer reading. For example, if the pointer must be moved clockwise to 1.000 on the scale, the screw should be turned counterclockwise. After making adjustments, allow the pointer to stabilize. During normal operation, the zero adjustment screw will require less than a 1/4 turn to set pointer to 1.000. If more than 1/2 turn is ever required, stop the motor and investigate the cause. Fig. 4 – Operating Instruction Plate
INSTRUCTIONS FOR OPERATION BEFORE STARTING, CHECK THAT: 1. Pointer and Lock Knob are in "LOCK" position. 2. RANAREX Selector Valve is in "O" position. 3. Silica gel in Drier is in active condition. 4. Gas vent hose is connected and ran to safe area. TO START: 1. With Inverter: Connect RANAREX card to Inverter outlet, turn switch "ON". Without Inverter: Connect RANAREX cord to correct current. 2. After 5 seconds, turn Lock Knob to "UNLOCK", observe as Pointer moves toward 1.000 reading. 3. Connect regulator delivery to 15 PSIG maximum. TO READ GAS: 1. Check if Pointer reads 1.000 on air. If not, reset with Zero Adjust screw. 2. For gas below 1.000, turn RANAREX Selector Valve to "LG." For gas above 1.000, turn RANAREX Selector Valve to "HG." 3. Connect gas hose to Flowmeter inlet. Adjust flow valve so float rises to approximate relative density. 4. After pointer stabilizes, read relative density. TO SHUT DOWN: 1. Disconnect gas hose from Flowmeter, then turn RANAREX Selector Valve to "O", Purge to 1.000. 2. Firmly turn Lock Knob to "LOCK" position. 3. With Inverter: Turn Switch "OFF" Without Inverter: Disconnect RANAREX cord from current.
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NOTE: Never turn the zero adjustment screw to the limit of the adjustments (clockwise or counter-clockwise) with motor operating.
3.1.2 Response Time{tc \l3 "3.1.2 Response Time} : When measuring gas at the normal flow rate of 12 SCFH, the response time to reach the final reading is 40-45 seconds. This time can be reduced by operating at a higher flow rate, obtained by adjusting the flowmeter valve so the float reads higher than the actual gas relative density. For example, when measuring 0.6 gravity gas, a flowmeter setting of about 1.2 will reduce the response time to about 30 seconds. However, the flow must not exceed the range of the flowmeter.
3.1.3 Over-Pressure Protection{tc \l3 "3.1.3 Over-Pressure Protection} : If the flowmeter valve is opened before the selector valve is turned to "LG" or "HG", the valve cover will lift off the body to relieve the pressure and will be reseated by the spring.
3.1.4 Purging to 1.000 After Measuring a Gas{tc \l3 "3.1.4 Purging to 1.000 After Measuring a Gas} : The instrument must be purged to bring the pointer within the range of the pointer lock mechanism. If the pointer starts toward 1.000 and then hesitates and remains at an intermediate reading, turn the selector valve halfway beyond "0" toward the next position. If the pointer then continues toward and reaches 1.000, check for an obstruction as described in the Troubleshooting Section .
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SECTION 4 MAINTENANCE AND SERVICING
4.1 LUBRICATION{tc \l2 "4.1 LUBRICATION} The motor bearings, impeller bearings and idler pulley bearings have long-life lubrication to provide long service. If the impeller bearings bind or become extremely noisy, they may be lubricated as described in the section titled Impeller Bearings , or the complete assembly may be replaced. The idler pulley bearing should be inspected and re-lubricated if it does not turn freely or becomes noisy.
4.2 SELECTOR VALVE{tc \l2 "4.2 SELECTOR VALVE} If the sample selector valve is contaminated, it will require cleaning and lubrication. Should this become repeatedly necessary, a gas filter should be used. To clean the selector valve, remove the screw at the center of the valve cover and withdraw the screw, 2 washers, spring and cover. Remove all old grease and contamination from the surfaces and channels in the cover and valve body. Lubricate the faces of the cover and body with silicone-based grease and replace all parts. If the valve cover or valve body become scored, it is necessary to lap/polish the mating surfaces to eliminate the scoring. Clean both surfaces, apply fine valve grinding compound to them and reassemble the valve. Loosen the detent spring which engages the "O", "LG" and "HG" notches of the cover. Repeatedly rotate the cover on the valve body beyond its normal operating range, continuing until the scoring is removed. After the lapping/polishing operation, thoroughly clean, lubricate and reassemble all parts.
4.3 POINTER LOCK{tc \l2 "4.3 POINTER LOCK} If the connecting tape leaves the cam or reference wheel while the gravitometer is in transit, the pointer lock will require adjustment in the following sequence: 1. Remove the front cover to check if the sides of the U-hook at end of lock spring are parallel with inner face of the cover, and if the set screw is fully tightened in the shaft of the lock knob. Turn the spring and tighten the screw if necessary. 2. Remove the indicating scale, track the connecting tape on the cam and reference wheel, then set pointer approximately at the 1.000 position. Hold front cover by hand in correct position on gravitometer casing. Turn the knob toward the lock position to check if the U-hook straddles the radial edge of the cam. If necessary, bend the spring in the correct direction at the knob shaft. 3. Hold the front cover to the casing by hand, turn knob toward lock position to check if the spring takes up the slack in the connection tape before the lower end of the spring snaps between the detent pins of the cover. If it does not, bend the upper section of the lock spring, at the knob, toward the cam edge. This will be toward the left when viewed from inside the cover. 4. Finally, with the cover held to the casing, check if the lower end of the lock spring will snap between the detent pins and will be retained. If necessary, bend the lower end of the spring toward, or away from, the front cover, as required.
4-1
MAINTENANCE AND SERVICING
4.4 CARE OF THE CONNECTING TAPE{tc \l2 "4.4 CARE OF THE CONNECTING TAPE} 4.4.1 Tracking the Tape{tc \l3 "4.4.1 Tracking the Tape} Release the pointer lock and remove the front cover and indicating scale. If tape does not track on both the measuring and reference wheels, turn both wheels clockwise. Replace the tape onto each wheel, set pointer to approximately 1.000 and turn the reference wheel to take up slack in the tape. If tape has fallen behind either wheel, extract it carefully by rotating the wheel as necessary, to avoid kinking the tape.
4.4.2 Cleaning the Tape{tc \l3 "4.4.2 Cleaning the Tape} Wipe off dust, finger marks, or oil with tissue or cloth. Do not use cleaning fluid or solvent. At the same time clean the rims of the cam and reference wheel.
4.4.3 Replacing the Tape{tc \l3 "4.4.3 Replacing the Tape} If a new tape must be installed, loosen the clip screws at the ends of the tape, remove retaining clips from the rims of the cam and the reference wheels and remove the old tape. Hook the new tape over the screw heads and install clips with curved end pointing in direction of tape. Adjust tape flush with edges of the wheels and tighten the clip screws. If spare tape is not available, a replacement tape can be made from 3M Company "Scotch" brand #175 Tenzar Recording Tape, or any other 1.5 MIL Heavy Duty Mylar Recording Tape. Cut tape to 13-9/16" long and punch 2 holes 9/64" diameter spaced 13-1/16" center to center. Check the operation of the pointer lock and if necessary, adjust it as described in Section 4.
4.5 DRIVE BELT TENSION{tc \l2 "4.5 DRIVE BELT TENSION} The correct tension required to prevent belt slippage without overloading the bearings is maintained by a spring loaded idler pulley. If dust or dirt accumulates between the idler pulley arm bushing and the pivot shaft, it will interfere with free motion and must be removed. Before disassembling, scratch a mark on the face of the adjusting collar and end of the pivot shaft to show the original positions. Obtain a firm grip on the collar by inserting a pin in a hole in the rim or face and loosen set screw. Allow collar to turn clockwise until spring tension is relieved, then draw collar and arm off shaft. After cleaning, reassemble in original position. The correct load of the idler pulley on the belt is 5 to 6 pounds which may be measured with a spring scale. Remove belt and place scale hook around pulley shaft. Pull on the scale in direction perpendicular to the normal position of the idler pulley arm until the pulley is swung into its normal position. If necessary to increase the load, turn the adjusting collar one quarter turn counterclockwise to the next flat of the pivot shaft. Before loosening the set screw, obtain a firm grip on the collar by inserting a pin in a hole in the rim of face.
4.6 IDLER BEARING{tc \l2 "4.6 IDLER BEARING} This bearing should be inspected and replaced if it does not turn freely or becomes noisy. NOTE: Bearing is lubricated as shipped. can be relubricated when necessary.
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It cannot be disassembled but
MAINTENANCE AND SERVICING
1.
Grip round shaft where it extends from pulley.
2. Remove adapter shaft by gripping hex section and turning for right-hand thread. Unscrew adapter shaft completely but do not lose split lock washer. 3. Insert tip of grease tube (PN 187-14010 or equivalent) into the tapped hole in the pulley shaft. Fill the hole with grease. 4. Replace adapter shaft in pulley shaft. recess around base of male thread.
Be sure split lock washer is in position in
5. Tightening the adapter shaft into the pulley shaft will force the grease into the bearings. Excess grease will be forced out through the seals but do not use more grease than needed to obtain smooth rotation of shaft in the pulley.
4.7 GRAVITOMETER DISASSEMBLY PROCEDURE{ tc \l2 " 4.7 GRAVITOMETER DISASSEMBLY PROCEDURE} If the gravitometer must be disassembled, the following sequence must be observed.
Front Cover: Release pointer lock and turn fully to UNLOCK position to set lock 1. spring below bottom of scale plate. Loosen the 8 fasteners but hold cover from dropping downward on scale and pointer. If cover is placed flat on bench-top, inside face must be upward to avoid damage to locking spring. 2.
Rear Cover:
Loosen the 8 fasteners to remove the rear cover.
3. Indicating Scale : Set pointer to about 0.950 and loosen scale fastening screws one turn. Lift scale up so keyholes will pass over screw heads. Then move scale downward holding it in until right side clears pointer. 4. Front Chamber Cover : Remove 8 screws around the rim of both chambers. Grasp assembly by scale posts and zero adjust screw and pull forward. The assembly may be set down on a bench-top against the 4 pins which project from the rear, or it may be placed on the right edge, steadied by the zero adjust screw. In this position exercise care that the pointer is not bent. 5. Rear Chamber Cover: First remove the Front Chamber cover. Then remove the belt and unscrew both impellers from front of the chambers; impellers have right hand threads. Remove 8 screws around rim of chambers and 2 inner screws at lower section of casting. Grasp assembly by bearing housing and pull outward from body. Assembly may be set on right edge, steadied by idler pulley, or may be placed on bench with pulleys downward. 6. (Front Chamber Cover, Chamber Body and Rear Chamber Cover): Operating Mechanism Remove front and rear covers, as previously described, and unscrew outlet nipples from right side of casing. Remove 2 outer screws from base of assembly accessible through rear. Remove 2 screws with carrying handle and internal spacer plate from upper section. Slide assembly to rear of the instrument, supporting it by hand and guided by pins in lower section.
4.8 IMPELLER BEARINGS{tc \l2 "4.8 IMPELLER BEARINGS} The impeller ball bearings are lubricated with sufficient grease for 2-3 years of operation. If the bearings do not turn freely or become noisy, the bearings should be replaced. The bearing part number is 5- 251. A design modification has been implemented to this assembly to improve its operating performance at low temperature as well as to simplify its service procedure.
4-3
MAINTENANCE AND SERVICING
The new design uses double seal ball bearings and additional o-rings to seal between the bearing (Key No. 1246/PN 5- 251) and the impeller shaft (Key No. 1247/PN 302-01889) and between the bearing and the impeller bearing casing (Key No. 1248/PN 302-01888). Use Part Number 300-00258 if ordering the complete bearing and shaft assembly. There is no need to fill the void between the impeller shaft and casing with bearing grease (P/N 187-14010). NOTE: All portable gravitometers with serial number P-259 and later incorporate the new design ball bearing assembly.
4.8.1 Impeller Disassembly{tc \l3 "4.8.1 Impeller Disassembly} a. Remove the front chamber cover assembly, impellers and rear chamber cover assembly from the operating mechanism per instructions 1-5 in the section titled Gravitometer Disassembly Procedure.
b. Temporarily reinstall front chamber cover assembly in instrument to avoid damage while working on bearings. c. Remove the nuts from the shaft without bending it. d. Mark the pulleys and shafts so that they can be reinstalled in their original positions. e. Gently tap on the end of the shafts to push the front ball bearing out of housing. Use small bearing puller to remove bearing from shaft. f. Gently push or tap on threaded end of shaft to push the rear bearing out of the housing. Use small bearing puller to remove bearing from shaft.
4.8.2 Impeller Assembly{tc \l3 "4.8.2 Impeller Assembly} a. Inspect and clean interior of impeller bearing casing and the shaft. b. Insert shaft and bearing into bearing casing. Replace the nuts on the ends of the impeller shafts. Install bearing on pulley end of shaft. Seat bearing bore against shoulder of shaft and turn shaft by hand to check for smooth rotation. c. Reassemble the rear chamber cover assembly, impellers, front chamber cover assembly in reverse order of disassembly.
4.9 TROUBLESHOOTING{tc \l2 "4.9 TROUBLESHOOTING} To be accurate the gravitometer must satisfy the following operating conditions: * * * * * * *
Sufficient flow of gas sample and reference air Impellers rotating at correct speed Pointer moves without friction Instrument free of internal leaks Pointer statically balanced Air drier filled with active silica gel Instrument is properly calibrated
If there is reason to believe the gravitometer is reading incorrectly, tests and remedies should be made in the sequence described below. If necessary to disassemble the gravitometer, refer to the Gravitometer Disassembly Procedure found earlier in this section.
4-4
MAINTENANCE AND SERVICING
1. Check the gas and air flow. Disconnect all inlet and outlet hoses, set selector valve to "O" and purge the gravitometer. Verify that there is flow at the discharge ports. If there is no evidence of flow, disconnect the hose from the rear of the air drier and retest. If flow is established, empty the air drier, clean the outlet elbow, fill with fresh silica gel (6-16 mesh) and retest. If there is no evidence of flow, remove the cover of the selector valve, inspect and clean the ports and channels of the cover and valve body and retest. Finally, if there still is no evidence of flow, it indicates the passages within the instrument are obstructed. Remove the rear chamber cover and check the passages which extend from impeller bearing location to the elbows near the bottom of the chamber cover. Also check the outlet tubes and nipples from both chambers. 2. Check the impeller speed. Correct speed is approximately 2800 RPM as measured with a strobe tachometer. If a tachometer is not available, remove the drive belt and verify that the motor pulley, impeller pulleys, and the idler pulley turn freely. If the impeller pulleys do not turn freely, lubricate the impeller bearings as described earlier in the section titled Impeller Bearings or replace the assembly. If the idler pulley does not turn freely, the motor should be replaced. 3. Check for frictionless indicator response. Remove front cover and connect the instrument to a gas sample. Record the reading. Gently move the indicator to each side of the true reading and release. Indicator should return to the same reading from each direction, within .001 relative density within 15 seconds. If it does not, the impulse wheel shafts and bearings should be cleaned. Remove the front chamber cover of the operating mechanism and hold it upright by gripping firmly in a vise, or stand it securely on right side edge. Loosen the set screws in the hub of the cam and reference wheel and draw the impulse wheels with shafts out of the bearings. Use care that the cam and reference wheels and the flexible tape are not damaged while removed from the instrument. Tag the impulse wheels to indicate the chamber from which they were removed. Polish the shafts with crocus cloth or fine steel wool. Do not bend the shafts. If the impulse wheel shafts show a bright polished groove where they rotate in the jeweled bearings, or if the hubs of the cam and reference wheel show a groove where they have been drawn against the ends of the impulse wheel bearings, these grooves should be removed by lapping and polishing. If the wear is excessive, the shafts must be replaced. Gently blow out the impulse wheel bearings with clean air or gas and add a drop of instrument oil to both ends of each bearing. Suitable oil is available from Chandler Engineering. Replace the shafts with wheels in their bearings in the correct chamber and turn them slowly. If the protruding portion of the shaft wobbles or if the wheel does not turn freely, the shaft should be replaced with a new one. A bent impulse wheel shaft will cause the instrument to lose accuracy and sensitivity. Attach the measuring and reference wheels to the impulse wheel shafts being certain that the set screws bear on the flats of the shafts. A small amount of shaft end play [.005" to 0.010" (.13-.25mm) maximum] must exist to prevent binding. Verify that no parts of the indicating mechanism have been bent and that there is no binding between parts. 4. Check for internal leaks. Operate the instrument connected to a gas sample and obtain a relative density reading at the far end of the measuring range. Shut off the gas flow by closing the flowmeter valve. The indicator should remain steady or should not return toward 1.000 reading at a rate faster than .007 on the inner scale in 3 minutes. If it does not meet this test, there is an internal leak. To determine where the leak is located, stop the motor, remove the front and rear covers and disconnect hose from the inlet port of the selector valve. Individually pressurize (approximately 10 psig) the upper and lower chambers with gas and use a gas leak detector to find the leak.
4-5
MAINTENANCE AND SERVICING
The leak is probably caused by loose screws or a gasket which has become damaged. Verify that the Tygon7 tubes which join the internal connector to the selector valve and to the elbows near bottom of rear chamber cover are not cracked or damaged. 5. Check the indicator balance. The measuring mechanism was statically balanced by the manufacturer and does not change with wear or age. The balancing weights behind the cam should not be disturbed. However, if required, the balance can be verified and restored as described below. Stop the motor and remove the front cover. Place the pointer consecutively at the right side, bottom, and left side of the scale. In each position tap the front of the gravitometer case to overcome static friction. The pointer should remain stationary or very nearly so. If it drifts more than two small graduations on the red scale, make compensating adjustments of the balancing weights on the threaded rods. When loosening or re-tightening the balancing weights, use care that the threaded rods, pointer and impulse wheel shaft are not bent or damaged. Balancing the cam and mechanism is a trial and error process. The pointer may be considered balanced if it remains steady or drifts only two scale divisions. After rebalancing, do not permit the weights to be moved. A drop of low strength Loctite7, lacquer, or fingernail polish on the weights and threaded rods will lock the adjustments is place. 6. Check the silica gel in the air drier. If silica gel is exhausted, remove and empty the air drier. Refill with active silica gel. 7. The gravitometer was accurately calibrated by the manufacturer and the calibration does not change appreciably with wear or age. The adjustments should not be changed without first checking every other possible source of error. Calibration should proceed if all other sources of error are eliminated. 8. Sometimes during calibration, repeatability problems occur due to static friction. Gently tapping the side of the case will eliminate the static friction.
4-6
SECTION 5 CALIBRATION
To calibrate the instrument there are three adjustments: 1. Zero Adjust. This is the only adjustment required in normal operation. The zero adjust screw operates the chain, sprockets and lower impulse wheel bearing which positions the lower impulse wheel longitudinally in the lower chamber to match the torque of the upper chamber when operating on air. Refer to the section titled Zero Adjustment in Section 3 for instructions for use of the zero adjust. 2. Sensitivity . The longitudinal position of the upper impulse wheel in the upper chamber governs sensitivity of the instrument. If the pointer is too sensitive, it may be reduced by moving the upper impulse wheel closer to the front of the chamber, by turning the upper impulse wheel bearing counterclockwise. If the pointer lacks sensitivity (and if there is no evidence of mechanical binding), it may be increased by moving the upper impulse wheel closer to the rear of the chamber, by turning the upper impulse wheel bearing clockwise. This adjustment requires loosening the 7/8" hex lock nut behind the measuring wheel, turning the 1/2" hex head of the bearing in correct direction, and tightening the lock nut. Turn only one flat (1/6 turn) at a time and retest. 3. Span Adjustment . The span of the gravitometer is governed by the angular position of the pointer on the measuring wheel. To permit adjustment, the pointer is attached to the measuring wheel by two screws which pass through circular slots in the pointer hub. If span adjustment is necessary, the pointer should be moved in relation to the measuring wheel in the direction of the desired reading. For example, if the pointer reads numerically too high on the red scale (too low on the black scale), the pointer should be moved clockwise. Similarly, if the pointer reads numerically too low on the red scale (too high on the black scale), the pointer should be moved counterclockwise. Before making an adjustment, mark the position of the pointer hub on the face of the cam, then loosen the screws just enough that the pointer can be turned against slight friction of the washers under the screw heads, but that it will not slip freely. Make adjustments in small increments of 2 or 3 small graduations on the red scale at one time and retest. When either the sensitivity or span adjustment is changed, it is necessary to reset the zero adjust to 1.000 on air.
5.1 CALIBRATION PULLEY{tc \l2 "5.1 CALIBRATION PULLEY} A Calibration Pulley is fastened inside of every new instrument. This pulley can be used, instead of a certified gas, to check the calibration of the instrument. The pulley, Part No. 315-03031, is intended to make the instrument read 0.640 theoretical relative density. Because of the tolerance on the diameters of the pulleys, the following test procedure must be used to determine the exact relative density ( .001) the pulley will produce. 1. Operate Gravitometer with new silica gel in the drier and the selector valve on "O". If necessary, turn ZERO ADJUST until pointer reads 1.000. 2. Turn power OFF; remove Upper Impeller Pulley and measure its maximum diameter at the crown with a micrometer. 3. Install the Calibration Pulley on the Upper Impeller Shaft. diameter at the crown, using the micrometer.
Measure its maximum
4. Continue to operate the gravitometer without making any adjustments. record the relative density reading.
Observe and
5-1
5. Divide the diameter of the standard Upper Impeller Pulley by the diameter of the Calibration Pulley and square the answer. This value is the correct relative density reading.
Example: Upper Impeller Pulley = 1.481" diameter (3.762cm) Calibration Pulley = 1.850" diameter (4.699cm) Correct Reading = !Syntax Error, {
6. If it is necessary to test the calibration at different relative density values, a Calibration Pulley is required for each test value. 7. After completing the tests, replace the Calibration Pulley with the standard Upper Impeller Pulley and store the Calibration Pulley for future use. The following additional calibration pulley sizes are available: CALIBRATION PULLEY SIZES
5-2
Part Number
Relative Density
Part Number
Relative Density
304-03031
(.758 S.G.)
309-03031
(.576 S.G.)
305-03031
(.715 S.G.)
320-03031
(.588 S.G.)
311-03031
(.733 S.G.)
322-03031
(.840 S.G.)
315-03031
(.640 S.G.)
324-03031
(.930 S.G.)
SECTION 6 PARTS LISTS
FIG KEY NO.
. PART No.
DESCRIPTION
NO
PORTABLE GAS GRAVITOMETER 1001
56-02253
Case
1
1002
300-00002
Front Cover Assembly
2
1003
357-02254
Rear Cover
4
1004
329-02044
Scale
1
1005
302-02145
Nameplate (State Serial Number)
1
1006
302-02080
Pointer Lock Knob
1
1007
188-11914
Fastener, Front Door
1
1008
187-20145
Retainer
1
1009
302-02267
Strap
1
1010
187-19521
Foot
1
1011
300-00046
Gas Flowmeter
1
1012
188-11923
Screw, 8-32 x 3/8", Pan Hd SS
1,4
1013
302-02573
Gas Hose
1
1014
300-00018
Selector Valve
1
1015
300-00259
Silica Gel (One Required for Refill)
1
1016
300-00017
Drier Box Assembly
1
1017
302-02294
Gasket
1
1018
302-02265
Drier Closure with Strap
1
1019
188-12573
Drier Fastener
1
1022
357-01954
Handle
1
1051
329-02067
Front Cover
2
1052
302-02144
Instruction Plate
2
1053
302-01930
Stop Collar
2
1054
188-07305
Set Screw,10-32x3/16",Hex Socket,Cup Pt.St.
2
1055
188-07566
Set Screw, 6-32x3/16",Hex Socket,Half Dog SS
2
6-2
FIG KEY NO.
. PART No.
1056
302-02081
Pointer Lock Spring
2
1057
187-19393
Window Clip
2
1058
188-00616
Screw,#4x1/4",Self Tapping,Rd Hd,ST,CAD PL
2
1059
357-01956
Window Gasket
2
1060
357-01955
Window Glass
2
1061
302-02040
Cam
3
1062
302-02208
Pointer
3
1063
302-02075
Tape Clip
3
1064
188-11706
Screw, 2-56 x 1/4", Nylok, Phillip Head,Steel
3
1065
188-11500
Screw,4-40X1/2",Fil Hd SS
3
1066
187-12161
Belleville Washer,#4,SS
3
1067
302-02001
Cam Hub
3
1068
187-00795
Small Balancing Nut
3
1069
302-28613
Large Balancing Nut
3
1070
302-20613
Balance Weight
3
1071
300-00007
Cam and Pointer Assembly
3
1072
302-02074
Balance Wheel Stop
3
1073
188-06992
Screw, 1/4-20 x 1/4", Rd Hd Br NI PL
3
1074
302-02160
Dust Sleeve
3
1075
188-12265
Set Screw, 6-32 X 1/2" Hex Socket Hd, Half Dog Pt,SS
3
1076
300-00005
Balance Wheel Assembly
3
1077
187-0006 187-15197
Electrical Receptacle (Below S/N P-5840) Electrical Receptacle (Above S/N P-5839)
3
1078
302-01958
Cover Gasket
3
1079
302-02042
Connecting Tape
3
1080
302-02194
Pointer Stop
3
1081
302-02139
Scale Stud
3
1101
188-11913
Screw,, 1/4-20 X 1/1-8" Oval Hd, SS
4
1102
302-02140
Spacer
4
1103
187-29445
Air Hose and Sample Hose
4
DESCRIPTION
NO
6-3
FIG KEY NO.
. PART No.
1104
302-02280
Hose Spring
4
1105/ 1106
302-02279
Tube & Connector
4
1107
187-11546
Drive Belt
4
1108
300-00256
Motor and Capacitor 115V 60HZ
4
1109
188-01857
Screw, 8-32 X 1/2" Fil Hd, SS
4
1110
188-01224
#8 SS Lockwasher, Spring
4
1111
302-02086 303-02298
Motor Pulley, 60HZ Motor Pulley, 50HZ
4
1112
188-11076
Set Screw, 10-32 X 5/16" Socket Hd, Cup Pt,SS
4
1113
188-11928
Dowel Pin, 1/4" x 1-1/4", SS
4
1114
356-03253
Base Plate
4
1115
188-04574
Screw, 5/16-18 X 1-1/4",Fil Hd, St Cad Pl
4
1116
302-02255
Elbow
4
1117
302-01970
Air Outlet Nipple
4
1118
187-02788
O-Ring, 1-1/32" O.D. x 1/4" wide, Rubber
4
1119
302-01969
Gas Outlet Nipple
4
DESCRIPTION
NO
OPERATING MECHANISM 1150
300-00003
Operating Mechanism Assembly (Also Order Two #1116)
5
1151
356-02057
Front Chamber Cover
5
1152
302-01880
Impulse Wheel
5
1153
187-07566
Set Screw, 6-32 x 3/16" Hex Socket Half Dog Pt, SS
5
1154
187-19961
Dowel Pin, 1/4"Dia x 1-1/2" SS
5
1155
302-02151
Impulse Wheel Bearing Locknut
5
1156
302-01920
Upper Impulse Wheel Bearing
5
1157
303-01919
Upper Impulse Wheel Shaft
5
1158
302-01930
Collar
5
1159
188-07305
Set Screw, 10-32 x 3/16", Hex Socket, Cup Pt,ST
5
1160
302-01929
Spacer
5
1161
302-01927
Zero Adjust Shaft and Sprocket
5
1162
302-03280
Zero Adjust Chain
5
6-4
FIG KEY NO.
. PART No.
1163
302-02147
Zero Chain Takeup
5
1164
188-11931
Screw, 1/4-20 x 7/8" Rd Hd SS
5
1165
188-05212
Lockwasher, 1/4" ST
5
1166
302-02161
Threaded Bushing
5
1167
304-01919
Lower Impulse Wheel Shaft
5
1168
302-01921
Lower Impulse Wheel Bearing and Sprocket
5
1169
188-12262
Lower Impuse Wheel Bearing O-Ring, 1/4"ID x 1/16"W, Neoprene
5
1170
188-00590
Screw, 5/16-18 x 1", Fil Hd ST Cad Pl
5
1171
188-14708
Spacer Ring
5
1172
188-14707
Grip Ring
5
1173
188-14706
Retaining Ring
5
1210
356-02056
Chamber Body
5
1211
329-02218
Front Chamber Gasket
5
1212
329-02126
Rear Chamber Gasket
5
1213
302-01881
Impeller
5
1214
302-01882
Inlet Plate
5
1215
187-11074
Inlet Plate O-Ring, 4-3/4"ID x 3/32"W, Neoprene
5
1240
356-02060
Rear Chamber Cover
5
1242
188-04577
Screw,5/16-18 x 1-1/2", Fil Hd, St Cad Pl, SS
5
1243
188-11928
Dowel Pin, 1/4" Dia x 1-1/4" St
5
1244
302-01883
Auxiliary Impeller
5
1245
300-00006 300-00258
Impeller Bearing Assembly (Below S/N P-8833) Impeller Bearing Assembly (Above S/N P-8832)
5
1246
5-251
Impeller Ball Bearing
5
1247
302-01889
Impeller Shaft (Below S/N P-8833 also include (3) 187-16721 Hex Nuts)
5
1248
302-01888
Impeller Bearing Casing
5
1249
302-01891
Impeller Pulley
5
1250
188-11076
Set Screw, 10-32 x 5/16", Hex Socket Cup Pt, St
5
1251
188-01084
Screw, 1/4-20 x 3/4, Fil Hd St Cad Pl
5
DESCRIPTION
NO
6-5
FIG KEY NO.
. PART No.
1252
302-27740
Idler Pulley Arm Shaft
5
1253
302-03030
Idler Pulley Arm Assembly
5
1254
188-00781
Set Screw, 10-32 x 5/16" Hex Socket Cup Pt,St
5
1255
302-02658
Idler Pulley with Bearing & Shaft
5
1256
302-02947
Idler Pulley Spring Tightener
5
1257
302-02946
Idler Pulley Spring
5
1258
302-01917
Idler Pulley Spring
5
1259
302-01916
Idler Pulley Arm Screw
5
1260
302-01892
Idler Pulley & Slide
5
1261
302-02657
Idler Pulley & Arm Assembly
5
1262
188-16720
Impeller Bearing O-Ring, 7/8"ID x 1/16"W, Buna-N
5
1263
187-11061
Retaining Ring, Inner
5
1264
187-19920
Retaining Ring, Outer
5
1265
187-19921
Retaining Ring Shaft
5
DESCRIPTION
NO
ACCESSORIES 1301
302-02195 302-03021
Cordset (Below S/N P-5840) Cordset (Above S/N P-5839)
5
1302
187-00259
Funnel
5
1015
300-00259
Silica Gel (1 required for refill)
1
329-02420
Inverter
187-16134
Replacement Tube & float for Flowmeter
187-15033
Transformer, Stepdown, 230-115VAC
187-14588
Portable Power Supply
302-20613
Balance Weight
302-28613
Long Nut
CALIBRATION PULLEYS
6-6
307-03031
Calibration Pulley (.758 S.G.)
308-03031
Calibration Pulley (.715 S.G.)
312-03031
Calibration Pulley (.733 S.G.)
314-03031
Calibration Pulley (.666 S.G.)
FIG KEY NO.
. PART No.
DESCRIPTION
316-03031
Calibration Pulley (.640 S.G.)
319-03031
Calibration Pulley (.576 S.G.)
321-03031
Calibration Pulley (.588 S.G.)
323-03031
Calibration Pulley (.840 S.G.)
325-03031
Calibration Pulley (.930 S.G.)
NO
6-7
6-8
6-9
6-10
