Humboldt HM-2315 User Manual

HM-2315_MAN_02.13

product manual

HM-2315

Volume Change Apparatus

Introduction:

The Humboldt Mfg. Co. Volume Change Apparatus consists of a two chamber,
reversible piston assembly mounted onto an enclosure which contains the flow
control valves and internal fluid lines. The apparatus uses two different methods
for measuring the volume change. The standard 100 cc Volume Change
Apparatus is designed to utilize either a standard LSCT or a Humboldt Digital
Gauge for measuring the volume change.

The Volume Change Apparatus comprises a change over valve system, which
provides an unlimited capacity by reversing the flow. Once again an LSCT and
bracket or Digital Gauge must be used for measurement.

Installation:
Using 1/8 inch O/D tubing, attach a fluid line from the pressure system into the
left hand side (when viewed from the front) of the Volume Change Apparatus
(Figure 1). Note: The tubing is to connect into the same side as the Volume
Change/Bypass control valve. Using the same sized tubing, run a line from the
right hand side of the Volume Change Unit (i.e. from the Flow Up/Flow Down
valve side) to the backpressure valve situated on the Triaxial Cell base pedestal.

To measure the volume change, you need to fit an LSCT with bracket or Digital
Gauge to the top of the Volume Change Unit.

With the left hand valve set to VOLUME CHANGE position and the right hand
valve set to FLOW UP position, slowly fill the top chamber with de-aired water
with the top bleed valve open to release any entrapped air. Once the chamber
is full and all the air has been bled, tighten the air release valve at the top of
the chamber. To fill the bottom chamber repeat the above procedure with the
two chamber assembly rotated 180 Deg. (i.e. upside down) and the Right Hand
Valve to FLOW DOWN.

It is advisable to leave this apparatus for at least 8 hours with an internal
pressure of 700 kPa (102 psi) so that any remaining trapped air can be absorbed
into the water. It is then necessary to flush out the Volume Change unit with
fresh de-aired water. It may be necessary to carry out this procedure more than
once if there are any signs of air pockets in the system.

The Humboldt 100 ml Volume Change Apparatus can be used with a 25 mm
LSCT and bracket, or can be purchased complete with a Digital Gauge. These
units are usually supplied to connect to an existing laboratory set up where
there are sufficient change over valves and panels within the pressure system to
enable the reverse flow. Sometimes these units are used directly in the pressure
line by connecting the upper chamber to the base of the Triaxial Cell and the
lower chamber receives the de-aired water. In such case, it is necessary to apply
a pressure to the top of the chamber after each test to reverse the flow. This
pressure could be taken from the cell pressure line. Calibration and de-airing
etc. is carried out as mentioned earlier.

Volume Change Measurement & Bypass

In order to measure the volume change, the left hand valve of the Volume
Change Apparatus must be set to VOLUME CHANGE position and the right
hand valve must be set to FLOW UP position or FLOW DOWN position.

During a test, water fills one of the chambers, while the other chamber is
opened and water drains out. As one chamber is filling and the other draining,
the piston will move inside the cylinder and the lever arm will move up or
down depending on which chamber is filling. The lever arm acts on the LSCT
or Digital Gauge which indicates the distance the piston has moved. This
information is then converted by the computer to volume change. During the
test, if the capacity of the sample exceeds the volume in one of the chambers,
it may be necessary to increase the volume change capacity. This is done by
reversing the flow direction. The flow direction is changed by switching the
FLOW UP/FLOW DOWN valve to the opposite direction. Note: When using
the reverse flow for greater capacity during a test, certain precautions should be
carried out when calibrating the apparatus (see calibration instructions).

By setting both valves to the BYPASS position, de-aired water can flow
through the change over valves system direct to the Triaxial cell. Volume is not
measured when the valves are in the Bypass position.

Calibration:

Switch on the power supply to the logger or monitoring readout unit with the
LSCT or Digital Gauge connected to it for at least one hour before attempting
calibration. Note: Some older monitors or loggers require a longer warm up
period. Please refer to your logger or read out unit guide.

With the probe of the transducer or Digital Gauge set to its maximum
downward position, set the monitor or logger to zero (if using a Digital Gauge,
set it to zero also). Note: The probe must still be in contact with the lever arm.

Adjust the right hand valve to the FLOW UP position until the maximum upward
movement has been achieved. Accurately measure the amount of water flowing
out with a measuring cylinder.

Alternatively you could work out the volume change by weighing the volume of
water displaced from the draining chamber. Weigh a beaker or other suitable
container with which to collect the water. Collect the water displaced when one
chamber is filled and the other drained. Weigh the beaker again with the water
displaced after the maximum upward movement has been achieved. Subtract
the empty container weight from the weight of the container and displaced
water. If the weight is measured in grams, this number will be the same as the
volume in millilitres or cubic centimetres.

Once the volume has been determined, the Digital Gauge should be set to
show the volume displaced and the logger or monitor should be adjusted to the
same volume.

This procedure should be carried out at least three times or until an acceptable
agreement between the measured volumes and the digital displays are
achieved.

Note: You should only attempt to calibrate in one direction.

Where more than 100cc of volume change occurs, you will need to reverse the
flow. You must therefore check the reverse displacement against the calibrated
readings. If necessary you may need to use a correction factor to overcome any
small hysteresis.

Warranty

Humboldt Mfg. Co. warrants its products to be free from defects in material or
workmanship. The exclusive remedy for this warranty is Humboldt Mfg. Co.,
factory replacement of any part or parts of such product, for the warranty of this
product please refer to Humboldt Mfg. Co. catalog on Terms and Conditions
of Sale. The purchaser is responsible for the transportation charges. Humboldt
Mfg. Co. shall not be responsible under this warranty if the goods have been
improperly maintained, installed, operated or the goods have been altered or
modified so as to adversely affect the operation, use performance or durability
or so as to change their intended use. The Humboldt Mfg. Co. liability under
the warranty contained in this clause is limited to the repair or replacement of
defective goods and making good, defective workmanship.

Humboldt Mfg. Co.

875 Tollgate Road
Elgin, Illinois 60123 U.S.A..

Testing Equipment for

HUMBOLDT

www.humboldtmfg.com

U.S.A. Toll Free: 1.800.544.7220

Voice: 1.708.456.6300

Fax: [phone]

Email: [e-mail]

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