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Pneumatic Pipe Plugs Mechanical Pipe Plugs Testing Equipment & Accessories

Pneumatic Pipe Plugs

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.

Cherne offers a 2 year warranty on all pneumatic plugs from date of manufacture, (plugs are post-dated by six months to allow for shelf time). If kept in controlled conditions (not exposed to sunlight and kept at temperatures between 0-125 degrees F) the pneumatic plugs remain in good condition for a longer period of time. Plugs should always be inspected for visual damage prior to every use.

Date codes on small test balls/long balls are two digit numbers (ex. 14). Date codes are changed each year on July 1st. Plugs manufactured on/after July 1st will bear the last two digits of the next year (ex. Plug manufactured on July 1st, 2014 would have a date code of 15). Larger plugs have the date codes stamped on the front of the plug. It will begin with the year, followed by a letter indicating the month, followed by a number for the day, and a letter for the unit produced. Example for a plug manufactured on February 14th, 2015 would read 15B14A.

Both our original long ball and our MS2 Long Balls are designed to seal wye fittings while conducting a sewer test. The MS2 Long Ball is unique as it features a relief valve, is multi-size, and inflates and deflates in stages to keep the work area dry by keeping the water from coming up through the pipe riser during the deflation process.

All of Cherne’s pneumatic pipe plugs are made from natural rubber. The only exception is our yellow pillow plugs which are made from a polyurethane impregnated fabric. 

Normal maximum temperature = 125° F. Normal minimum temperature = 0° F. Consult factory if you wish to use plug at temperatures outside this range.

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.

Cherne Urethane pillow plugs, Well Monitor plug and the Petro Econ-O-Grip can be used with most hydrocarbons. Contact Cherne engineering for specific applications.

Yes. Cherne publishes a chart that pairs up our pneumatic pipe plugs with some of the most popular sizes of elliptical pipes. It can be found on Cherne’s website at

Generally speaking pneumatic plugs that don’t have sealing rings may be eligible for patching. The damage to the plug cannot be any longer than 4", or deep enough to penetrate the cording. Plugs cannot be patched more than 4 times. Other repairs can also be made, like replacing inflatable bladders, bypass hoses, castings and fittings. When in doubt, ask the customer to take digital pictures of the damaged area and email it to you. Forward the pictures to the Cherne QA Dept. along with a description of the damage for final determination.

Inflation pressure should be checked a minimum of once every 4 hours while a pneumatic plug is in use.

The bypass cap or plug is removed and replaced with an Air Loc Conversion Kit.

There are patch kits available for Urethane plugs. Other plugs that can be patched or have the bag replaced, are as follows; 15"–30", 24"–42", 20"–40", 24"–48", 24"–60", 48"–72" and 54"–96"

Feet of head is the height of water over the center line of the plug.

This answer depends on how the plug is maintained. If the instructions are followed in the Cherne Safety Instruction Manual, it is not unusual for the plug to last for many years. If the instructions are not followed, a plug can be destroyed during the first use. Cherne pneumatic plugs come with a 2 year warranty from date of manufacture.

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.

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.

Mechanical Pipe Plugs

Yes. Cherne offers two chemical resistant mechanical plugs: The Cherne Well Monitor Plug and the Cherne Petro Econ-O–Grip.

Gripper plugs have natural rubber O-Rings. These O-Rings allow for operating temperatures between 0° F to 125° F. Consult engineering for usage outside this temperature range.

Mechanical plugs can be used to block an opening (Grippers are mechanical plugs). Be sure to use the correct size Gripper for the opening.

Yes. Cherne offers the T-Handle Gripper as a flow through plug.

Deflection is defined as the “out of roundness” of plastic pipe after being covered with backfill (stone, sand, dirt, etc.).

“Base Inside Diameter” is average inside diameter less manufacturing tolerances for out of roundness and wall thickness. The ASTM uses base ID to calculate deflection allowances.

4" to 15"

18" to 48"

7.5% deflection is maximum amount of deflection allowed by ASTM. The trade has adopted 5% deflection as the standard maximum deflection allowed off “Base Inside Diameter”, which is a more stringent test. 

Both pipes have the same outside diameter. SDR 35 has a thinner wall that SDR 26.

Yes.  See the line of cherne mechanical cleanout plugs.  The 4" version has a fill and drain hose.

Yes. The #012678 Tub Plug Set.

Testing Equipment & Accessories

The Poly Lift Line products are ideal for plugs up to 15" in diameter. 

Material Safety Data Sheets for smoke bombs and liquid smoke can be found at

Diaphragm Hydrostatic test pumps use oil in the engine, in the gear reduction unit, and in the pump itself. 30 weight motor oil is used for the engine and pump. The gear reduction unit uses 90 weight gear lube.

**Piston Pumps only use oil in the engine.  (30 weight motor oil.)

Smoke bombs have a one year shelf life from the date of manufacture.


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.

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.

Yes. View our video demonstrating how a joint tester works or refer to the owner’s manual here.

3.5 psi.

Owner’s Manuals and parts lists on all Cherne equipment can be located in the technical section of the Cherne website.

Concrete pipe is porous and the ASTM guidelines give allowances for this porosity.

5 Seconds

3.5 PSI with less than a 1 PSI pressure loss over the time period called out in the tables. 

The shelf life on the mineral oil used in liquid smoke is indefinite.

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Each disc seal will include a double bladder. This means two bladders will be included in the purchase of each disc seal. The double bladders are engineered to provide a leakproof seal.

Cherne has designed the disc seals by using a lightweight, corrosion-resistant aluminum. The disc seals also include handles that assist for easy transporting and installation.

The disc seal sizes range from 24 inches to 96 inches.

Part Number  Disc Seal Size Max Back Pressure Bypass Diameter Weight
102418  24 IN 5 PSI 2 IN 65.52 LB
102718  27 IN 5 PSI 2 IN 74.72 LB
103018  30 IN 5 PSI 2 IN 85.07 LB
103318  33 IN  5 PSI 2 IN 95.05 LB
103618  36 IN 5 PSI 2 IN 105.38 LB
103918  39 IN 5 PSI 2 IN 126.72 LB
104218  42 IN 5 PSI 2 IN 138.35 LB
104518  45 IN 5 PSI 2 IN 150.32 LB
104818  48 IN 5 PSI 2 IN 162.69 LB
105418  54 IN 5 PSI 2 IN 188.45 LB
106018  60 IN 5 PSI 2 IN 215.58 LB
106618  66 IN 5 PSI 2 IN 244.06 LB
107218  72 IN 5 PSI 2 IN 329.34 LB
107818  78 IN 5 PSI 2 IN 367.29 LB
108418  84 IN 5 PSI 2 IN 405 LB
109018  90 IN 5 PSI 2 IN 444.39 LB
109618  96 IN 5 PSI 2 IN 485.13 LB

5 PSI.

Cherne Disc Seals are designed to block flow or provide bypass flow in underground pipes with a low backpressure. Used for pipe construction, rehabilitation, cleaning and testing, these plugs can be separated into two halves to effortlessly fit through any manhole.

Smoke bombs have a one year shelf life from the date of manufacture. The shelf life on the mineral oil used in liquid smoke is indefinite.

5 seconds

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