Which water heater pan should be used when installing a water heater?
The plastic pan is not approved for gas water heater installations, and the aluminum pan must
be used. The plastic and aluminum pans are approved for electric water heater installations.
What is the test pressure for ASTM C924 (concrete pipe)?
3.5 PSI with less than a 1 PSI pressure loss over the time period called out in the tables.
How long does it take to test a joint with no more than 1 PSI drop?
5 seconds
Why is the testing time longer for plastic pipe than concrete pipe with comparable lengths and diameters?
Concrete pipe is porous and the ASTM guidelines give allowances for this porosity.
Can I order specific parts for a Honda test pump?
Owner’s Manuals and parts lists on all Cherne equipment can be located in the technical section of the Cherne website. http://www.cherneind.com/Data/ “pieces parts” – replacement parts for the hydrostatic test pumps and joint testers. We do not stock engine parts.
What is the test pressure called out in ASTM C1103 for joint testing?
3.5”
Why is it important to know pounds of force calculation?
This calculation is important to the end user and helps them understand the forces behind the plug so that they can decide the proper way block the plug.
What is the definition of feet of head, and the formula to calculate the back pressure?
Backpressure is measured either in terms of feet of head or psi.
Feet of Head. Simply stated “feet of head” is the height of water above the centerline of a plug. For vertical pipe the calculation is easy. Simply measure the height of the pipe and that is the footage of head pressure. For horizontal pipe, feet of head is still simply the height of water above the plug. There are various ways to determine this height base on knowledge of the actual application. For example, if you have a 300’ long section of pipe at a 1 degree slope, the feet of head is 3’. (300*.01)
PSI - This measurement is typically done with a pressure gauge.
#’s (pounds) of Force. This is the calculation to determine how much force is being held back by a plug. It is useful information when trying to design a plug blocking system for a specific job.
Calculating pounds of force for air pressure tests.
PSI *square inches of pipe opening = #’s of force
Example: 8” and 5 psi test. Pipe area = Pi R2 * (3.14*42=.50.24”). 50.24” * 5 PSI = 251.2 #’s of force.
Calculating pounds of force for head pressure applications.
Convert Feet of Head to PSI and then do calculation above.
PSI = Feet of Head *.434.
Example: 8” pipe at 30’ of head. Pipe area = Pi R2 * (3.14*42=.50.24”) 30 Feet of Head *.434 = 13.02 13.02 * 50.24 = 654 lbs. of force.
One foot of head to psi conversion chart is attached for your reference. Feet of head psi ratings for each Cherne plug can be found in the Cherne catalog.
How much vacuum (inches of mercury) do manholes need to be tested to?
10 inches
What is the shelf life of smoke bombs?
Smoke bombs have a one year shelf life from the date of manufacture.