Carpet Thickness Tester | Working Principle of Shirley Carpet Thickness Tester

Name of the Experiment: Determination of carpet thickness by Shirley thickness tester.

Introduction:
Carpet is a floor-covering textile having surface formed from yarns or fibres projecting from a substrate. Fabric thickness is a parameter of fabric which involves handle, creasing, wrinkle resistance, thermal resistance and other fabric properties. A carpet is compressible and therefore it is necessary to specify at what pressure its thickness is to be measured.
Shirley thickness tester
Shirley thickness tester
Objective:
To determine the thickness of carpet and understand its related facts.

Theory:
Anderson and Clegg state: Thickness as estimated by eye is similar to that measured by an instrument at low pressure, and by measuring thickness at increasing and decreasing pressures in the range exerted by a human foot, pressures of the order of 0-12 lb/in2 normally being encountered, we can obtain a measure of the behaviour of carpets to imposed loads. Essentially the determination of fabric thickness consists of the precise measurement of the distance between two plain parallel plates when they are separated by the cloth, a known arbitrary pressure between the plates being applied and maintained. It is convenient to regard one of the two plates as the pressure foot and the other as anvil. The Shirley thickness tester has such two parallel plates. The upper plate serves as a collar and supports for the additional load which produce pressure. The dial gauge is graduated in mm which indicates the thickness of the carpet.

Apparatus:
  1. Shirley thickness tester
  2. Carpet
  3. Knife
  4. Scale.
M/c specification:
  • Name: Shirley thickness tester
  • Manufacturer: Shirley Developments Limited, Manchester.
Atmosphere:
  • Testing atmosphere: Relative humidity - 65%+/-2% & Temperature - 270+/-20C.
  • Present atmosphere: Relative humidity - 68% & Temperature - 290.
Procedure:
  1. At first we will take our sample carpet and cuts it with a knife.
  2. Place the carpet on the lower plate and bring down the upper plate on it.
  3. Load the dead weight on the collar and takes the reading from the dial gauge.
  4. Now add the other additional weights one after another on the collar to increase the weight.
  5. And take the readings from the dial gauge.
  6. After taking the last reading we will wait for 5 mins for the action of the weights on the carpet.
  7. Then we will again unload the weights from the collar one by one and take the reading of the thickness.
  8. From the beginning thickness and the last thickness of the carpet after compression we will find out the compression of the carpet and the recovery percentage.
Data:
S/n
Adding load (gm)
Total load (gm)
Thickness (mm) after loading
Thickness (mm) after unloading
1
90 (dead wt.)
90
12.8
12.5
2
200
290
12.7
12.5
3
300
590
12.6
12.5
4
500
1090
12.5
12.4
5
1000
2090
12.4
12.3
6
1000
3090
12.3
12.2

Calculation:

  • Compression = (12.8 - 12.5) mm = 0.3 mm
  • Recovery = 2.4%
Result:
Compression of the carpet = 0.3 mm and recovery = 2.4%.

Graphical Representation:
We can make a chart of loading and unloading on carpet thickness by placing the values of load or unload in Y axis and thickness in X axis. It is shown below:
Graphical Representation
Remark:
The thickness of the carpet is compressed very little and so it may say that its load bearing capacity is good and its durability will be long. Again its recovery percentage is poor which indicates that if it is bended once it will not serves long which indicates that its service ability is poor.

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