Blocking Plugs

What is the difference between a Test Ball and a Muni Ball?

Test Ball and Muni Ball are trademarked names. A test ball does not have a bypass and it is designed to do one job, blocking (sealing) a pipe. A Muni Ball has a bypass tube that runs through the plug that allows the user to bypass effluent through the tube, or with an adapter cap, it can be converted to complete an air test. Muni Balls can also be used for blocking pipe as well.

How is it determined what size plug should be used?

The first step is to determine the ID (inside diameter) of the pipe that will be plugged, and then choose the plug that matches the ID of the pipe for that application. Some of our Cherne plugs can be used for multiple sizes of pipe, but they should only be used when the size range of the plug is being used on a pipe which falls within that range. When in doubt, call the customer service help desk.

Is there a formula used to calculate backpressure?

Backpressure is defined in PSI (pound per square inch) or feet of head. 

Simply read the gauge pressure for PSI. 

For feet of head, calculate height of water over the centerline of the plug. 

Example; 100’ line at 1% slope with a 10’ manhole (100 x .01) + 10 = 11 feet of head.