R
Design Guide
Tank Heating Systems
C H E M E L E X
Contents Introduction Design Guide Overview Appropriate Applications Design Guide vs. TankCalc Plus Approvals Preliminary Steps Caution
1 1 1 1 1 1
Part I: Heat Loss Calculations Surface Areas Step 1. Calculate the surface area of the tank. Cylinder Surface Area Truncated Cone Surface Area Step 2. Calculate the QV (heat loss through the insulated body). Step 3. Calculate the QS (heat loss through the base support). Concrete Slab or Earth Foundation Legs Concrete Saddles Uninsulated Skirt Step 4. Calculate the QA (heat loss through the accessories). Manholes Handholds Step 5. Calculate the tank QT (overall heat loss) Step 6. Calculate the final-design heat loss Illustrative Example
2 3 3 4 4 6 6 7 8 9 10 10 10 11 11 12
Part II: Heater Selection and Sizing System Selection Plastic Tank Considerations RHS Model and Size Selection Illustrative Example RHS Tank Heater Dimensions
13 14 15 15 16
Part III: Heater Design Thermostatic Control of Tank Heaters Location, Spacing, and Arrangement of Heaters Questions
17 17 18
Specifications/Approvals
19
Design Worksheet
20
Notes
22
Introduction Design Guide Overview This design guide has three basic parts: • Part I provides heat-loss information based on various tank configurations and temperatures and helps you calculate tank heat loss. • Part II helps you determine which Raychem Heating System—the Raychem Heating System (RHS) tank heater or self-regulating heating cables—is right for you. If you choose an RHS tank heater, Part II helps you select the right system model and size. If you choose a heat-tracing cable system, Part II will refer you to the right source. • Part III contains design instructions for both systems.
Appropriate Applications This design guide is appropriate for the following conditions: • Fully insulated tanks • Vertical and horizontal tanks • Low (water) and medium (light oils) viscosity fluids • Ordinary areas • Standard freeze protection and process temperature maintenance Contact Raychem for designing systems that meet the following conditions: • Hazardous locations • High viscosity fluids (heavy oils) • Tanks smaller than 4 feet in diameter • Other unusual applications
Design Guide vs. TankCalc Plus This guide presents a general approach to designing a heat-tracing system for a tank or vessel. The guide’s design and heat-loss assumptions are based on those in Raychem’s TankCalc Plus software. The heat loss calculations made using this guide will be higher than the identical calculation in TankCalc due to engineering assumptions made in this guide. See your Raychem representative for a copy of TankCalc.
Approvals RHS tank heaters are approved for ordinary areas and Class I Division 2, Class II, and III, Division 1 and 2 hazardous locations by Factory Mutual (FM) and the Canadian Standards Association (CSA).
Preliminary Steps Before proceeding with your tank heating system's design, you should obtain the information requested in the Design Worksheet at the end of this design guide and record the necessary information there.
1
Part I: Heat Loss Calculations Surface Areas The overall heat loss (Q T) of an insulated tank can be expressed as: QT = QV + QS + QA where: Q V = Heat loss through the insulated body of the tank Q S = Heat loss through the slab, legs, saddle, or other base support Q A = Heat loss through accessories such as manholes, handholds, ladders, or handrails Calculation of the tank’s overall heat loss (Q T) requires six simple steps: Step 1. Calculate the surface area of the tank. Step 2. Calculate Q V (heat loss through the insulated body of the tank). Step 3. Calculate Q S (heat loss through the base support). Step 4. Calculate Q A (heat loss through the accessories). Step 5. Calculate Q T (overall heat loss). Step 6. Calculate the final-design heat loss. The heat-loss rates for insulated tank bodies (Table 2 and Chart 2 on page 5) are based on the following IEEE 515 provisions: • Fiberglass insulation • Tank located outdoors in winds greater than 20-mph • No insulating airspace between tank surface and insulation The tank body heat-loss rates in Table 2 and Chart 2 assume a tank that is completely full and insulated with a minimum of 1 inch of fiberglass. However, Table 3 provides insulation factors for adjusting the tank-body heat loss to insulations other than fiberglass.
2
STEP 1. Calculate the surface area of the tank. Cylinder Surface Area The surface area of the cylindrical tank (Figure 1) is equal to the area of the body (Abody) plus the area of both ends of the tank (Aend), or, in the case of a vertical cylinder resting on a slab, the area of the tank body (Abody) plus the area of the top (Aend). If the tank is a vertical cylinder resting on a slab, do not add in the bottom area at this point.
H D
H
D
Figure 1. Cylinder surface areas To calculate the total surface area (AV) of the tank cylinder: • Calculate the surface area of the body: (Abody) = πDH • Calculate the surface area of one or both ends: (Aend) = πD 4
2
or
(Aend) = πD x 2 4 2
• Add the results. For your convenience, Table 1 below provides both the end and body areas of cylindrical tanks 6 to 20 feet in diameter and 8 to 25 feet high. Table 1. Cylindrical Tank Surface Areas Abody (ft2) H (ft) D (ft)
Aend (ft2) 8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
29 39 51 64 79 95 114 133 154 177 202 227 255 284 315
170 198 227 255 283 311 340 368 396 425 453 481 509 538 566
189 220 252 283 315 346 377 409 440 472 503 535 565 597 629
208 242 277 311 346 381 415 450 484 519 553 588 622 657 692
227 264 302 340 377 415 453 491 528 566 604 641 679 717 754
245 286 327 368 409 450 491 531 572 613 654 695 736 776 817
264 308 352 396 440 484 528 572 616 660 704 748 792 836 880
283 330 377 425 472 519 566 613 660 707 754 802 849 896 943
302 352 403 453 503 553 604 654 704 754 805 855 905 955 1006
321 374 427 481 535 588 641 695 748 802 855 908 962 1015 1069
340 396 452 509 565 622 679 736 792 849 905 962 1018 1075 1131
359 418 478 538 597 657 717 776 836 896 955 1015 1075 1135 1194
311 440 503 566 629 692 754 817 880 943 1006 1069 1131 1194 1257
396 462 528 594 660 726 792 858 924 990 1056 1121 1188 1254 1320
415 484 553 622 692 761 830 899 968 1037 1106 1175 1244 1314 1383
434 506 579 650 723 795 868 940 1012 1084 1157 1229 1301 1373 1446
453 528 604 679 754 830 905 981 1055 1131 1207 1282 1357 1433 1508
471 550 629 707 786 864 943 1021 1100 1179 1257 1336 1414 1493 1571
151 176 202 227 252 277 302 327 352 377 403 427 452 478 503
Note: For area of horizontal tank, add area of both ends.
3
Truncated Cone Surface Area The total surface area (Av) of a truncated cone tank (Figure 2) is calculated as follows: (Av) = (Abody) + (Atop) + (Abottom)* * Do not include (Abottom) if tank bottom is resting on a slab.
Abody = π (D+d) S 2
D
= H
S
π (D+d) 2
Atop =
π D2 4
Abottom =
π d2 4
(D+d)2 + H2 4
d
Figure 2. Truncated Cone Surface Areas
STEP 2. Calculate the QV (heat loss through the insulated tank body). Calculating the QV requires the following tank information: • Maintain temperature (TM) • Minimum ambient temperature (TA) • Insulation thickness You use the maintain and minimum ambient temperatures to arrive at the ∆ temperature. With the ∆T and the insulation thickness you calculate the QV. To calculate the QV : • Obtain the ∆T by subtracting the minimum ambient temperature (TA) from the maintain temperature (TM):
∆T = (TM) – (TA) • Determine the heat loss rate for the application. (Table 2 and Chart 2 on page 5 show the heat-loss rates per square foot for typical ∆ temperatures and insulation thicknesses.) • Determine the insulation factor. (Table 3 on page 5 provides insulation factors for the most commonly used tank insulations.) • Calculate the total heat loss through the tank body: QV = AV x Heat loss rate x Insulation factor
4
Table 2. Heat Loss Rate per Square Foot (watts/ft2) Insulation Thickness ∆T
1"
1 1/2"
2"
3"
4"
50°F 100°F 150°F 200°F 250°F 300°F
3.4 7.1 11.0 15.3 20.0 24.9
2.3 4.8 7.5 10.3 13.5 16.8
1.7 3.6 5.6 7.7 10.2 12.7
1.2 2.4 3.7 5.2 6.8 8.5
0.9 1.8 2.8 3.9 5.1 6.5
30
Heat Loss (watts/ft2)
25
1" of insulation
20 1 1⁄2" 15 2" 10
3" 4"
5 0 50°
100°
150°
200°
250°
300°
∆T (°F)
Chart 2. Heat Loss Rate per Square Foot (watts/ft2)
Table 3. Insulation Factors for Typical Insulations Insulation types
Insulation Factor
k Factor*
Fiberglass Cellular glass Calcium silicate (Type 1) Expanded perlite Flexible elastomer Mineral fiber blanket Polyisocyanurate Rigid polyurethane, preform Rigid polyurethane, spray Rock wool/mineral wool
1.00 1.46 1.48 1.85 1.15 1.26 0.67 0.60 0.60 1.06
0.270 0.395 0.400 0.499 0.311 0.340 0.180 0.161 0.161 0.287
* Based on a 50°F mean temperature with units BTU/hr–°F–ft2/in.
5
STEP 3. Calculate the QS (heat loss through the base support). The following heat-loss tables and accompanying charts (3A–3D) provide typical base-support heat losses (QS) through the following types of base support: • • • •
Concrete slab or earth foundation Legs Concrete saddles Uninsulated skirt
Concrete Slab or Earth Foundation Based on the ∆T and tank diameter, select the QS from the table or chart below.
Table 3A. Heat Loss for a Concrete Slab or Earth Foundation ∆T (°F)
Tank Diameter (ft) 5 10 20 30 40 50
50°
100°
150°
200°
250°
300°
137 283 566 848 1131 1374
278 573 1163 1767 2388 2945
451 864 1760 2616 3518 4320
566 1154 2325 3535 4649 5891
711 1452 2922 4383 5906 7265
857 1703 3488 5231 7037 8836
10000 9000
D = 50 feet
8000
Heat Loss (W)
7000
D = 40 feet
6000 D = 30 feet
5000 4000
D = 20 feet 3000 2000
D = 10 feet
1000
D = 5 feet
0 50°
100°
150°
200°
250°
∆T (°F)
Chart 3A. Heat loss for a concrete slab or earth foundation.
6
300°
Legs Determine the heat loss for legs (QS) as follows: •
Based on the ∆T and tank diameter, select the heat loss from the table or chart below.
•
The heat loss is on a per leg basis; therefore, multiply the heat loss by the number of legs.
Table 3B. Heat Loss for a Leg Support Tank Diameter (ft)
∆T (°F) 50°
100°
150°
200°
250°
300°
5 10 and above
26 85
52 169
77 351
103 336
129 420
155 505
600 D = 10 feet and up
Heat Loss (W)
500 400 300 200
D = 5 feet 100 0 50°
100°
200°
150°
250°
300°
∆T (°F)
Chart 3B. Heat loss for a leg support.
7
Concrete Saddles Determine the heat loss for saddles (QS) as follows: •
Based on the ∆T and tank diameter, select the heat loss (QS) from the table or chart below.
•
Multiply the heat loss you select by the number of saddle supports.
Chart 3C. Heat Loss for a Concrete Saddle Tank Diameter (ft)
∆T (°F) 50°
100°
150°
200°
250°
300°
5 10 15 20
93 145 198 250
186 290 395 500
275 430 586 741
368 576 783 991
461 721 981 1241
553 866 1179 1491
1600 D = 20 feet 1400
Heat Loss (W)
1200
D =15 feet
1000 D = 10 feet 800
600
D = 5 feet
400
200
0 50°
100°
150°
200° ∆T (°F)
Table 3C. Heat loss for a concrete saddle.
8
250°
300°
Uninsulated Skirt Based on the ∆T and tank diameter, select the QS from the table or chart below.
Table 3D. Heat Loss for an Uninsulated Skirt Tank Diameter (ft)
∆T (°F) 50°
100°
150°
200°
250°
300°
5 10 15 20
402 806 1209 1613
805 1612 2419 3225
1193 2389 3585 4780
1595 3195 4794 6393
1998 4000 6003 8006
2400 4806 7212 9619
10000
D = 20 feet 9000 8000
D = 15 feet
Heat Loss (W)
7000 6000 5000
D = 10 feet
4000 3000
D = 5 feet 2000 1000 0 50°
100°
150°
200°
250°
300°
∆T (°F)
Chart 3D. Heat loss for an uninsulated skirt.
9
STEP 4. Calculate the QA (heat loss through the accessories). The following heat-loss tables and accompanying charts (4A–4D) provide typical accessory heat losses (QS) through the following types of accessories: • Manholes • Handholds • Ladders • Handrails Manholes Select the heat loss for a manhole from the table or chart below. The heat loss is based on a 2-foot-diameter cover and a 1-foot-tall base. The base and cover are uninsulated. Table 4A. Manhole Heat Losses
Heat Loss (W)
∆T (°F) 50° 564
100° 1120
150° 1680
200° 2237
250° 2807
300° 3401
3500
Heat Loss (W)
3000 2500 2000 1500 1000 500 0 50°
100°
150° 200° ∆T (°F)
250°
300°
Chart 4A. Manhole heat losses.
Handholds Calculate the heat loss for handholds as follows: • Select the heat loss from the table or chart below based on the ∆ temperature. Heat loss from the table or chart is based on a 0.5-foot-diameter, uninsulated surface. • Multiply the heat loss you select by the number of handholds. Table 4B. Heat Loss for a Handhold
Heat Loss (W)
10
∆T (°F) 50° 90
100° 178
150° 265
200° 351
250° 437
300° 526
600
Heat Loss (W)
500 400 300 200 100 0 50°
100°
150° 200° ∆T (°F)
250°
300°
Chart 4B. Heat loss for a handhold.
STEP 5. Calculate the tank QT (overall heat loss). Add the heat loss rates (QV, QS, and QA) from Steps 2, 3, and 4.
Outdoor application QT = QV + QS + QA
Indoor application QT = 0.9 x (QV + QS + QA)
STEP 6. Calculate final-design heat loss. Raychem recommends that the final-design heat loss should include a 20 percent safety factor, to satisfy IEEE 515 and manufacturing tolerances. Final design heat loss = QT x 1.20 Note that this same heat-loss calculation approach is appropriate for insulated polypropylene and fiber-reinforced plastic (FRP) tanks.
11
Illustrative Example Tank Checklist Maintenance temperature Minimum ambient temperature Tank material Tank shape Tank dimensions Insulation type Insulation thickness Tank support type Tank accessories Tank location
110°F –10°F Metal Vertical cylinder 10-foot diameter; 12 feet high Fiberglass 2 inches Concrete slab 1 manhole Outdoors
STEP 1. From Chart 1, the area (AV) of the tank sides and top is 377 + 79 = 456 square feet STEP 2. ∆T = 110°F – (–10°F) = 120°F For 2 inches of insulation and 120°F ∆T, the surface heat loss rate is 4.4 watts/square foot. The insulation factor for fiberglass is 1.0. QV = AV x Heat Loss Rate x Insulation Factor Interpolation on the graph is needed to determine the heat loss rate.
(
)
Heat loss rate = 3.6 + 120°F - 100°F (5.6 - 3.6) 150°F - 100°F Heat loss rate = 4.4 w/ft For this example QV = 456 x 4.4 x 1.0 = 2007 watts STEP 3. Using the graph in Step 3 to determine the heat loss (QS) through the concrete slab for a tank diameter of 10 feet and a ∆T of 120°F: QS = 689 watts STEP 4. For a ∆T of 120°F, the manhole heat loss can be determined from Step 4: QA = 1344 watts STEP 5. QT = QV + QS + QA QT = 2007 + 689 + 1344 = 4040 watts STEP 6. Calculate final-design heat loss, which includes a safety factor of 20 percent. Design heat loss = 4040 watts x 1.20 = 4848 watts
12
Part II: Heater Selection and Sizing System Selection To select the appropriate Raychem heater for a tank, many factors have to be considered. Use following guidelines to determine the best product for your application, but if you have any questions, contact your Raychem sales representative. RHS Tank Heaters Choose an RHS tank heater for the following special applications: • A space constrained tank • A heat-loss application requiring fluid heat-up • Tanks with high heat loss If you choose an RHS tank heater, proceed to “RHS Model and Size Selection” on page 15. Self-regulating Heating Cables Choose a self-regulating heating cable for the following special applications: • A tank containing temperature-sensitive fluids • Tank materials such as PVC and polyethylene • Applications requiring: — Shut-off at a specific temperature — Uniform heating • An application in a Class I Division 1 hazardous area (refer to the Raychem Factory Mutual Approved Auto-Trace Heat Tracing Systems for Division 1 Locations Application and Installation Guide, H53622) If you choose self-regulating heating cables, please consult one of the following design guides for model and size selection and for additional design information: • Auto-Trace Heat Tracing Systems for Ordinary and Division 2 Areas Design Guide, H51149 • Factory Mutual Approved Auto-Trace Heat Tracing Systems for Division 1 Locations Application and Installation Guide, H53622.
13
Plastic Tank Considerations When designing heating systems for plastic tanks, the user must be careful to keep the wall temperature below the recommended maximum material temperature. The following steps will quickly help you determine if your specific application is appropriate for the tank material.
STEP 1. Determine the power density of the -L heater, Qa. a) Qa = 295 Btu/ft2-hr for nominal voltages of 120 Vac and 240 Vac b) For voltages other than 120 Vac and 240 Vac, (Qa) adjusted = (Qa) * (V/ Vnominal)2 STEP 2. Determine the maximum fluid maintain temperature, Tf. STEP 3. Determine the fluid gradient, ∆Tf. The fluid gradient will depend on fluid type and temperature. For applications not involving temperature sensitive fluids, the following values may be used for simplicity. ∆Tf = 10°F for fluids similar to water ∆Tf = 30°F for fluids similar to warm light oils ∆Tf = 100°F for fluids similar to warm heavy oils STEP 4. Calculate the tank wall gradient, ∆Tw. The gradient depends on wall thickness, t and material conductivity, k. ∆Tw = Qa * t / k Wall thickness is expressed in inches. Typical conductivity values for high temperature plastics are: k = 1.7 Btu-in/hr-ft2 -°F for polypropylene k = 2.1 Btu-in/hr-ft2-°F for fiber-reinforced plastic (FRP)
STEP 5. Calculate the maximum outer wall temperature, Tout-max. Tout-max = Tf + ∆Tf + ∆Tw The user should contact the tank manufacturer to determine the type and temperature capability of the tank material. The maximum temperature for polypropylene and FRP is typically 220°F. Other plastics like PVC and polyethylene have much lower temperature capabilities and are more suitable for use with Raychem's self-regulating heating cable product line.
Illustrative Example Tank Checklist Fluid Tank material RHS heater Area Classification
Water FRP RHS-L-XXX Ordinary
Maintenance temp. Tank wall thickness Voltage
50°F 1⁄2” 277 Vac
STEP 1. Calculate adjusted heater power density , (Qa) adjusted = (295) * (277/ 240)2 = 393 STEP 2. Determine fluid maintain temperature, Tf = 50°F STEP 3. Determine fluid gradient for water, ∆Tf = 10°F STEP 4. Calculate wall gradient for a FRP tank with 1⁄2” wall thickness, ∆Tw = (393 * 0.5) / 2.1 = 94°F STEP 5. Calculate maximum outer wall temperature, Tout-max = 50°F + 10°F + 94°F = 154°F Maximum material temperature for FRP is approximately 220°F. Therefore, the application is compatible with the tank material.
14
RHS Model and Size Selection Tank material and power density determine which RHS tank heater series to select. The number of heaters you will need depends on the amount of heat distribution the application requires. A large number of low-powered heaters will disperse the heat better than fewer high-powered heaters. Raychem recommends distributing the heat over as much wall surface as is economically feasible. If you have any questions, contact your Raychem sales representative.
Metal Tanks RHS-H series heaters are used for metal tanks. RHS-H heaters have a power density of 1.9 watt/in2 at specified voltage with integrated thermostatic overtemperature protection. The table below lists the RHS-H configurations available. To determine the number of heaters required, divide the final-design heat loss for the tank by the heater's power output as shown in the table. Catalog Number
Dimensions
Voltage (Vac)
Power Output (W)
RHS-H-500-1 RHS-H-1000-1 RHS-H-1400-1 RHS-H-500-2 RHS-H-1000-2 RHS-H-1400-2
14" x 24" 24" x 26" 24" x 36" 14" x 24" 24" x 26" 24" x 36"
120 120 120 240 240 240
500 1000 1400 500 1000 1400
Polypropylene, FRP and Metal Tanks RHS-L series heaters are for plastic or metal tanks. RHS-L heaters have a power density of 0.6 watt/in2 at specified voltage with integrated thermostatic overtemperature protection. The following RHS-L configurations are available: Catalog Number
Dimensions
Voltage (Vac)
Power Output (W)
RHS-L-150-1 RHS-L-300-1 RHS-L-420-1 RHS-L-150-2 RHS-L-300-2 RHS-L-420-2
14" x 24" 24" x 26" 24" x 36" 14" x 24" 24" x 26" 24" x 36"
120 120 120 240 240 240
150 300 420 150 300 420
Power Adjustment Factors For all heaters with the -2 option, power output is calculated at 240 Vac. If the source voltage is either 208 Vac or 277 Vac, the following power output correction factors should be used. 208 Vac: 277 Vac:
Power output factor = 0.75 Power output factor = 1.33
15
RHS Tank Heater Dimensions
B
A
D C
E F
Dimensions (inches)
16
RHS Model
A
B
C
D
E
F
RHS-L-150-W RHS-H-500-W
14
24
4.875
8.875
4
5.125
RHS-L-300-W RHS-H-1000-W
24
26
9.95
13.75
4
5.125
RHS-L-420-W RHS-H-1400-W
24
36
9.75
13.75
4
5.125
Part III: Heater Design Thermostatic Control of Tank Heaters RHS Tank Heaters Thermostatic control is required with RHS tank heaters. There are two kinds of sensors for indicating temperature: “in-fluid” and “on-surface” sensors. The “in-fluid” approach uses a thermowell protruding through the tank wall and into the fluid. Control of the heater is achieved by using a solid-state control device that receives its input from an RTD inside the thermowell. The “on-surface” approach uses bulb and capillary thermostats to control tank heaters by sensing temperatures on the outside surface of the tank wall. The Raychem BCK-35 clamp kit is used to attach the bulb sensor to the wall. Also use AT-180 aluminum tape over the bulb. Primary thermostats should be located midway between RHS heaters. If your application has high-heat-loss supports or accessories, place the primary thermostat midway between the RHS heater and the support or accessory. The primary thermostat bulb should be placed horizontally on the tank. RHS tank heaters have integrated, resettable thermostats that provide overtemperature protection in the event of a primary thermostat failure. The RHS integrated thermostat should not be used as the primary means of temperature control.
17
Location, Spacing, and Arrangement of Heaters For vertical tanks, locate the heater on the lower one-third of the tank wall. Spiral self-regulating heating cables around the tank as indicated on Figure 3. Optimum spacing between spirals is 6 inches and minimum spacing is 3 inches. Use AT-180 to attach self-regulating heating cable to the tank. Arrange heaters on horizontal tanks and vertical cones as shown in Figures 4 and 5, respectively.
A
B
Primary thermostat bulb
Primary thermostat bulb
Figure 3: Vertical tanks with RHS (Figure A) and self-regulating heating cables (Figure B) heaters.
A
B
Figure 4: Horizontal tanks with RHS (Figure A) and self-regulating heating cables (Figure B) heaters.
A
B
Figure 5: Truncated cones with RHS (Figure A) and self-regulating heating cables (Figure B) heaters.
Questions For more detailed answers to specific application problems, contact your local Raychem representative.
18
Specifications/Approvals RHS Tank Heaters Description The RHS family of tank heaters consists of constant-wattage heating pads suitable for installation on metal and plastic tanks. The heaters come with power outputs up to 1400 watts. Contact Raychem for customizing RHS heaters for special applications. Voltage Watt density Corrosion resistance T-ratings Maximum exposure temperature Maximum maintain temperature
120–277 Vac 0.6 and 1.9 W/in2 at rated voltage. Stainless steel and silicone rubber construction T2C (446°F/230°C) for -H series heaters T4A (248°F/120°C) for -L series heaters 366°F (166°C) Up to 200°F (93°C) for -H series heaters Up to 120°F (49°C) for -L series heaters
For use on metal tanks only Catalog Number
Power Voltage Density (W/in2) (Vac)
Nominal Output (W)
Overall Dimensions
RHS-H-500-1 RHS-H-1000-1 RHS-H-1400-1 RHS-H-500-2 RHS-H-1000-2 RHS-H-1400-2
1.9 1.9 1.9 1.9 1.9 1.9
500 1000 1400 500 1000 1400
14" x 24" 24" x 26" 24" x 36" 14" x 24" 24" x 26" 24" x 36"
120 120 120 240 240 240
For use on polypropylene, FRP, and metal tanks Catalog Number
Power Voltage Density (W/in2) (Vac)
Nominal Output (W)
Overall Dimensions
RHS-L-150-1 RHS-L-300-1 RHS-L-420-1 RHS-L-150-2 RHS-L-300-2 RHS-L-420-2
0.6 0.6 0.6 0.6 0.6 0.6
150 300 420 150 300 420
14" x 24" 24" x 26" 24" x 36" 14" x 24" 24" x 26" 24" x 36"
120 120 120 240 240 240
RHS Installation Kit Description The RHS Installation Kit (P/N 844869) is FM Approved and CSA Certified for use with RHS tank heaters. The RHS Installation Kit contains a caulking gun, two RTV adhesive tubes, a wedge, one 30-foot roll of AT-180 tape, and a trowel for mounting up to two RHS tank heaters.
Approvals FM APPROVED
Ordinary and Hazardous Locations
®
Class I, Div. 2, Groups B, C, D Class II, Div. 1 & 2, Groups E, F, G Class III All hazardous location applications must be engineered by Raychem. T-ratings: Low-watt heaters: High-watt heaters (Class I): High-watt heaters (Class II & III):
T4A T2C Contact Raychem
19
Design Worksheet
Tank Information Tank reference Maintenance temperature
(°F/°C)
Minimum ambient temperature
(°F/°C)
Maximum ambient temperature
(°F/°C)
Max. heater exposure temp. (power off) (must be less than 366°F (166°C)
(°F/°C)
Process maintenance operating temperature (power off)
(°F/°C)
Start-up temperature
(°F/°C)
Insulation type and thickness Tank wall material
❏ Metal
❏ Plastic
Tank location
❏ Outdoors
❏ Indoors
Maximum circuit breaker load
Amps
Supply voltage
Vac
Chemical exposure
❏ None
❏ Mild inorganic
Tank location
❏ Indoors
❏ Outdoors
Required approvals
❏ FM
❏ CSA
Area classification
❏ Nonhazardous
❏ Hazardous
Class
____________
Div. ____________
Flammable substance(s)
____________
T-rating(s)
____________
Ignition temperature(s)
____________
(°F/°C)
____________
(°F/°C
❏ Organic/corrosive
If hazardous:
20
Group
____________
Tank Top/Ends (Select one)
❏ Flat ❏ Half dome ❏ Full dome ❏ Cone
Height
(ft/m)
❏ Vertical cylinder
Diameter
(ft/m)
Height
(ft/m)
❏ Horizontal cylinder
Diameter
(ft/m)
Length
(ft/m)
❏ Rectangular
Length
(ft/m)
Width
(ft/m)
❏ Spherical
Diameter
(ft/m)
❏ Truncated cone
Height
(ft/m)
Diameter
(ft/m)
❏ Truncated pyramid
Height
(ft/m)
Length
(ft/m)
Cross sect.
(in2/cm2) Perimeter
(in/cm)
Cross sect.
(in2/cm2) Perimeter
(in/cm)
Quantity
Cross sect.
(in2/cm2) Perimeter
(in/cm)
Quantity
Diameter
(ft/m)
Height
(ft/m)
Quantity
Diameter
(ft/m)
Height
(ft/m)
❏ Ladders
Contact pts
Cross sect.
(in2/cm2) Perimeter
(in/cm)
❏ Hand rails
Contact pts
Cross sect.
(in2/cm2) Perimeter
(in/cm)
Tank Body (Select one)
Height
(ft/m)
Width
(ft/m)
Tank Bottom/Ends (Select one)
❏ Flat ❏ Half dome
Supports (Select one)
❏ Legs
Quantity
❏ Open skirt ❏ Saddle ❏ Slab Accessories (Select all that apply)
❏ Manholes Insulated sides: ❏ Yes Insulated top: ❏ Yes
❏ ❏
No No
❏ ❏
No No
❏ Handholds Insulated sides: ❏ Yes Insulated top: ❏ Yes
21
Notes
22
Chemelex, Raychem, and TankCalc are trademarks of Raychem Corporation.
Raychem Corporation Chemelex Division Industrial Products Group 300 Constitution Drive Menlo Park, California 94025-1164 Tel (800) 545-6258 Fax (415) 361-6711
Raychem Canada, Ltd. 6303 Airport Road, Ste 101 Mississauga, Ontario Canada L4V 1R8 Tel (800) 387-3993 Tel (905) 671-1680 Fax (905) 671-0972
Raychem S.A.I.C. Carlos Pellegrini 1363, Piso 8 1011 Capital Federal Buenos Aires, Argentina Tel (54) 1/394-5150 Fax (54) 1/326-9985
©1995 Raychem Corporation Printed in USA H55208 12/95
All information, including illustrations, is believed to be reliable. Users, however, should independently evaluate the suitability of each product for their application. Raychem makes no warranties as to the accuracy or completeness of the information, and disclaims any liability regarding its use. Raychem’s only obligations are those in the Standard Terms and Conditions of Sale for this product, and in no case will Raychem be liable for any incidental, indirect, or consequential damages arising from the sale, resale, use, or misuse of the product. Specifications are subject to change without notice. In addition, Raychem reserves the right to make changes—without notification to the Buyer—to materials or processing that do not affect compliance with any applicable specification.
