Table of Contents
| This article will discuss the Testing of Sewer After Laying Pipe. |
A sewer is an underground conduit or pipe ( generally closed but normally not flowing full ) used to convey sewage to the point of disposal or discharge.
✓ After laying the pipe, the sewer should be tested before backfilling and finishing. Sewers are usually subjected to the following test:
i. Straightness test
ii. Obstruction test
iii. Air test
iv. Water test
Testing of Sewer After Laying Pipe
i. Straightness test
✓ A straightness test is done by placing a mirror at one end of the sewer and a lamp at the other.
✓ If a pipeline is straight, the full circle of light can be observed otherwise apparent.
ii. Obstruction test
✓ By inserting a smooth ball of diameter 13 mm from the upper end and letting it roll downward.
✓ If there is no obstruction in the sewer line, the ball shall roll down the pipe’s invert and emerge at the lower end.
iii. Air test
✓ If there is no sufficient water and the size of the pipe is larger, air testing is done by plugging the sewer at both ends.
✓ From one end, the hand pump gives air pressure equivalent to 100 mm of water.
✓ If the pressure is maintained at 75 mm of water, the joint is assumed to be watertight.
iv. Water test
Provide sufficient time to set joints before the test.
✓ Plug the lower end of the pipe and fill it with water for five days. Read the initial level of water. Find the water required to restore the original level after 30 minutes.
Limit:
For small diameter: 150 ml/m in length
For large diameter: 600 ml/m in length
| Read Also: System of sanitation. |
