Determination of water resistance by Shirley Hydrostatic Head tester

March 8, 2023 by Kazi Md. Rashedul Islam

Content Index hide

Introduction:

Objectives:

Apparatus:

Standard testing temperature:

Preparation of specimen:

Working Procedure:

Result:

Conclusion:

Introduction:

Fabric’s water resistance refers to its ability to resist wetting and penetration by water. Water resistance refers to the amount of force or pressure applied to textile material to keep water out, and determining this required force or pressure is very important for any particular use of the fabric. This pressure of water is determined using a Shirley Hydrostatic Head tester. This instrument has a double-chambered specimen holder; the inner chamber of the chamber has a diameter of 5 cm. In order to clamp circular specimens over the orifice, rubber gaskets are used. The distilled water contained in the outer chamber is forced up against the specimen by compressed air entering the outer chamber through tube B and displacement into the inner chamber. With the help of a skirt, the clamp prevents air from leaking continuously across the specimen from the inner chamber to the outer chamber or to the environment. The tube is connected to a manometer, and the pressure of water against the fabric is shown on the manometer tube’s adjustable scale. Approximately 3 liters of air supply are used for the test, and are fed through flow control devices from sources of 4-20 inches/pound. A flow control device is designed in such a way that once it is set to increase pressure by 10 cm per minute, the rate of loading will be in the specified limits of cm per minute. 150 cm of water is the maximum head that can be achieved.

Objectives:

To know about water resistance of fabric.
Come to learn about The Shirley hydrostatic head test.
Working procedure of the Shirley hydrostatic head test.

Apparatus:

The Shirley Hydrostatic Head Tester
Specimen(Canvas fabric)
Scissor.
Template.
Water.

Standard testing temperature:

An atmosphere at the prevailing barometric pressure with a relative humidity of 65% and temperature of 20⁰ C is called standard testing temperature.

Preparation of specimen:

Hydrostatic head testers require fabrics with a diameter of 6 cm for the test of fabric resistance in Shirley. We cut circular specimens of fabric 6 cm in diameter so as to represent the material available as fully as possible. With an appropriate template, they can be marked and cut with scissors while handling the material as little as possible. Or, they can be cut with a circular knife directly.

Figure: The Shirley Hydrostatic Head Tester

Working Procedure:

At first, the test cell is rinsed thoroughly with distilled water and filled to approximately 0.3 cm to the top.
The inner rubber gasket should be thoroughly dried by wiping it with a clean absorbent cloth and laying a test specimen over it. In the same manner, the clamp is clamped into place and screwed down.
Now, the pressure on the under surface of the specimen is allowed to increase at the specified rate of lading until water appears at a third place in the specimen.
While the air supply and test cell discharge to atmosphere, the manometer remains at the pressure at which the test specimen broke down. In this way, the value can be noted at leisure.
The manometer scale is designed so that the hydrostatic head may from one arm of the U-tube manometer to the accuracy required by B.S. 2823:1957.
When we will see, three drops of water appear on the fabric the reading is taken from the dial.
At the same way, we test 5 specimen and calculate average of air pressure.

Result:

Finally we found, the water resistance of our fabric is 41.6 cm water pressure.

Conclusion:

Fabric water resistance depend on the fabric types and fabric’s finishing process. Our fabric’s water resistance is 41.6 cm water pressure. From this experiment, we came to learnt about the Shirley hydrostatic head tester and it working process. This experiment will help in our future life. Thanks to our teacher to help us.