H1 manual

H1 Gravimetric Hydraulics Bench

USER GUIDE

© TQ Education and Training Ltd 2005 No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage and retrieval system without the express permission of TQ Education and Training Limited. All due care has been taken to ensure that the contents of this manual are accurate and up to date. However, if any errors are discovered please inform TQ so the problem may be rectified. A Packing Contents List is supplied with the equipment. Carefully check the contents of the package(s) against the list. If any items are missing or damaged, contact your local TQ agent or TQ immediately.

PE/DB/1105

TQ H1 Gravimetric Hydraulic Bench

CONTENTS Section

Page

1

Introduction

1

2

Installation instructions

2

Electrical Connection

2

Filling and draining operations

3

Additional sump connection (stack pipe)

4

3

Weight measurement technique

6

4

Routine care and maintenance

9

General

9

Specific Faults

9

Bench Supply (gate) valve leak

10

i


ii


1. Introduction The TQ Volumetric Hydraulic bench H1 is a self-contained and fully mobile bench comprised of four major parts: i)

The Sump Tank (160 Litre capacity), containing the water necessary for the experiments.

ii)

The lid (or bench top).

iii)

The Weigh Tank (40 Litre capacity), suspended from a bracket at the top of the sump just under the lid.

iv)

The Electric Submersible Pump held in place by a bracket in the base of the sump tank.

The H1 bench provides an accurately controlled flow of water, for use with many experiments. The top of the H1is rigid and forms the working surfaces for several experiments in the TQ Hydraulics range. The principle of operation is straightforward; the user measures the time taken for the weigh tank to collect a specific weight of water. The weight of the water is measured by a counter balanced lever and weight system with a 3 to 1 ratio. Six weights, each 2 kg (12 kg total) allow a measurement of 36 kg water.

Weight of water in the weigh tank = 3 times the balancing weight.

Figure 1. H1 Gravimetric Bench - General Layout

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2. Installation instructions The Hydraulic Bench is usually despatched in its assembled condition with the exception of the drain valve. The weight carrier, weights and drain valve are packed separately.

This manual uses symbols to attract the operator’s attention to particular information. These symbols and their meanings are as follows:

NOTE

Important information

CAUTION

Failure to carry out this instruction could cause damage to the apparatus, other equipment, personal property, or the environment

WARNING

Failure to carry out this instruction could cause personal injury

Electrical Connection

WARNING

Connect this apparatus to earth

NOTE

The colours of the wires in the mains lead supplied follow this code:

GREEN-AND-YELLOW: BROWN: BLUE:

NOTE

EARTH (E or ) LIVE (L) NEUTRAL (N)

Protect the installation with a residual current circuit breaker with a trip current of 30 mA. The supply fuse rating must be either 5 A (for a 230 V supply) or 10 A (for a 115 V supply).

WARNING

Always isolate this equipment from the electrical supply before accessing any of its electrical components.

WARNING

Do not use this apparatus within 2.4 metres of a mains electrical outlet.

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Filling and Draining Operations 1. Disconnect the electrical supply to the Gravimetric Bench 2. Remove the bench top: a) With the help of an assistant carefully lift and remove the bench top, allowing the bench supply hose to slide back through its hole in the bench top. b) Place the bench top safely onto suitable supports, do not rest the bench top on its side or it may be damaged. 3. Ensure that the sump, weigh tank and pipes are clean and free from dust. 4. Fill the sump tank with around 160 Litres of cold water to the level label (See Figure 2).

Figure 2

5. Mix the Barley Straw water treatment liquid in the correct proportion to the contents of the sump tank. Close the bench supply (gate) valve. 6. Connect bench to the mains and start pump motor. Check hose clips for leaks. 7. Direct the supply hose into the weigh tank and slide the weigh beam stop (See Figure 5) over the beam. Remove the weights. 8. Open the bench supply (gate) valve and fill the weigh tank with water to roughly 25 mm from the top. 9. Close the bench supply (gate) valve and check the drain valve is closed and not leaking. 10. To drain the weigh tank, depress the weigh beam above the weight hanger and slide the beam stop away. Gently release the weigh beam and the water will commence to drain. 11. To finish draining, lift the weigh beam for 10 to 15 seconds. Note: There will always be water in the drain valve tube and some residual water in the bottom of the weigh tank after draining.

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12. Replace the bench top, the Gravimetric Bench is now ready for use.

The drain valve assembly (A) drops into the hole in the weigh tank (B) (See Figure 3). The rubber seal, plus the weight of the valve assembly when filled with water, ensure a good seal.

Figure 3 Assembly of water valve into weigh tank

To drain the sump tank a)

Disconnect the bench from the electrical supply.

b)

Place the bench near to a ground level drain.

c)

Uncouple the stack pipe (See Figure 4) from inside the sump tank and carefully lower it towards the ground level drain (place a finger over the end of the pipe to prevent spillage while lowering). In the final stages of emptying, with the help of an assistant, tip the tank at a slight angle towards the drain.

d)

Replace the stack pipe

Additional sump connection (stack pipe). The stack pipe provides an additional sump connection, allowing the H1 apparatus to be used as a sump and measuring circuit to any hydraulic circuit required. Remember that the H1 sump tank has a maximum capacity of 160 litres.

The Gravimetric bench H1 is not suitable for accurately measuring flow rates above 2 kg per second. This is mainly due to the capacity of the weigh tank and the increased turbulence at higher flow rates, which will give false readings.

Referring to Figure 4, the procedure for connection is as follows:

a)

Remove the bench top as described in Filling and Draining Operations. Page

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b)

A stack pipe from the sump is secured next to the normal delivery pipe, held in place with a plastic clip and worm drive hose clip.

c)

Remove the worm drive clip and slide the pipe through the hole in the tank and out of the plastic clip. The stack pipe can now be connected to the external circuit.

Note: The outlet can be connected with the sump tank full of water if the connection can be made above the level of the sump tank water.

d)

Replace the bench top.

To replace the stack pipe, reverse the above procedure.

Figure 4. Stack pipe arrangement (Viewed from inside the tank)

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3. Weight measurement technique The precision weighing unit of the TQ Hydraulic Bench, which has a 3:1 arm ratio, is designed for accurate measurement of large quantities of water up to a maximum of 36 kg.

Before continuing with any experimental work on the bench, students should familiarise themselves with the following technique:

1. Have the TQ HAC10d stopwatch or other suitable timing device in readiness. 2. Close the bench supply (gate) valve and direct the supply hose into the weigh tank through the hole in the centre of the bench top. 3. Slide the weigh beam stop (See Figure 5) out of line of the beam and lift the beam for 10 - 15 seconds to ensure the weigh tank is empty.

Figure 5. Weigh beam stop

4. Allow the weigh beam to return to its lower position with only the weight carrier on (see Figure 6). Slide the weigh beam stop above the weigh beam.

Page

6 of 10


a) Stop positioned over beam b) Start pump c) Drain valve closed

Figure 6

5. Switch on the pump. 6. Open the bench supply valve. 7. Start timing the instant the weigh beam becomes horizontal and place selected mass immediately on to the weight hanger. (See Figure 7 and Figure 8 ).

a) Beam moves to horizontal b) Start clock

Figure 7

a) Add required weights

Figure 8

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8. When the mass of water collected balances the mass of the weight hanger, the beam will rise again to the horizontal position (See Figure 9). At this instant, stop the timer and record the timing interval.

a) Beam moves to horizontal b) Stop clock

Figure 9

Note: Water mass = 3 x hanger weight

9. Close the supply valve or switch off the pump.

a) Drain b) Press down on A c) Slide stop away d) Release arm gently and remove weights e) Lift at B to complete draining for 10 15 seconds Figure 10

10. To drain weigh tank, depress weigh beam above weight hanger and slide weigh beam stop away. Gently let weigh beam rise until it stops against the sump tank. Remove the weights and the tank will continue draining. As the weigh beam returns to the horizontal, lift it for 10 - 15 seconds to drain final amount from weigh tank (See Figure 10). Note: With the supply (gate) valve fully open, a flow of 30 kg in 30 seconds is usual and is the acceptable test at the factory.

Page

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4. Routine care and maintenance General 

Periodically inspect electrical leads and connections for wear and that all warning labels are in position and readable.



Every 3 to 4 months drain the sump tank and wipe clean with a damp lint-free cloth. Refill with clean water and stain and deposit inhibitor.



Where heavy contamination has taken place on the tanks, a proprietary household cleanser may be used if applied sparingly. (It is advisable to try the chosen cleanser on a small area before applying all over).

Specific Faults PUMP OVERHEATS:

Check for sufficient water in the sump tank and that the pump is not running dry.

PUMP OUTPUT LOW: Check the following points:

1.

The water level in the sump tank. Excessive noise coming from the pump section is one sign of a low water level. Refill the tank if necessary.

2.

Blockages of the bench (gate) supply valve. Remove the bench top and the flexible plastic supply pipe at the valve and visually check for blockages.

3.

Foreign matter in the pump and suction pipe.

To check the pump: (a)

Disconnect the H1 from the electrical supply

(b)

Remove the bench top as described in Filling and Draining Operations.

(c)

Drain the sump tank

(d)

Disconnect the hose connections on the pump

(e)

Lift the pump free of the location bracket

(f)

Check the bottom (inlet area) of the pump for any foreign matter.

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Bench Supply (gate) valve leak The bench supply valve is a commercial gate valve. Figure 11 shows the internal details of the valve. Cure slight leaks as follows:

1. Remove the Hand wheel retaining nut and the Hand wheel.

2. Slacken and remove the cap nut. The gland-packing ferrule will now be exposed. The head of the ferrule should be about 2 mm clear of the thread. If this is not the case, simply refitting and tightening the cap nut may correct the leak. However, if the ferrule is flush with the thread, then the gland needs repacking. To do this:

a)

Remove the existing packing and repack with either replacement nylon ‘0’ rings or packing cord.

b)

Refit the gland ferrule and nut, ensuring the gland ferrule has enough clearance to tighten the packing when the nut is refitted.

Figure 11. The Internal workings of the gate valve

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H1 manual

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