Protect Yourself From Potential Failure of the Devices that are Supposed to Protect You

Large diameter appliances and externally mounted relief valves are found on many rigs.  These devices are critical for safe operation when working with high volume large diameter hose.  An often overlooked issue, is the testing of the relief valves on these appliances.  An improperly adjusted relief valve can lead to a few dangerous issues including but not limited to;

• Burst supply hose due to hose service pressure below the relief valve pressure (Supply grade LDH-200 PSI)
• Failure to open in an overpressure
• Opening at too low of a pressure and dumping critical water, which may be a nuisance, or cause icing.

Some hose testing companies offer appliance testing, but many do not.  For departments that conduct hose testing,  these appliances should be tested along with your hose, at least annually, with the consideration given to more frequently.  Kochek, a large manufacturer, recommends every 6 months.

Here are two links that reinforce the necessity for testing of the appliances;

http://www.state.nj.us/dca/divisions/dfs/reports/hampton_township_ff_Injury_rpt.pdf

http://www.chenangofireems.com/uploads/files/Manifold%20Failure%20Test%20Report.pdf

This is the result of an appliance failure.  Courtesy Lambertville, NJ FD

In both of the previous reports, it was fortunate that there were no fatalities.  Be cautions around these appliances, at all times, not just when testing them.

Testing isn't to be taken lightly.  Any time you are service testing equipment, you should expect it to fail, that is, to take the proper precautions to prevent injury and damage.  Proper head, eye, body and foot protection are a must.  Following appropriate testing standards is another important consideration.

NFPA 1962 recommends testing of appliances to the manufacturers standards.  Kochek happens to offer a guide for doing just such a test.  It can be found here; http://www.kochek.com/docs/PressRelief_Valv_%20TestProc_Web.pdf  Within the 1962 document, there lacks substantial step by step guidance, but rather it has general recommendations.  The document can be viewed at www.nfpa.org

When you raise the throttle, the gauge will "pop" when the relief dump valve on the appliance opens and should not rise above that as the pump pressure continues to rise.

Testing these appliances can be done in house, if you follow the above recommended guidance.  A few points to note are as follows;

• Expect a catastrophic failure of an appliance.  If the appliance has ever been dropped or damaged, and not inspected, it should be removed from service and checked by a qualified professional, to include x-ray inspection of applicable.  Invisible manufacturing flaws may not be evident, use care.
  
• It is a good idea to attach the appliance being tested to a section of hose to move it away from the rig and personnel prior to testing.  CAUTION:  Check the service pressure of the hose you are using, and do not exceed it.  This means that standard supply grade LDH (single jacket rubber type) will not be sufficient for testing over 200 PSI.
  
• Inspect the devices for any obvious corrosion or deficiencies prior to testing.
• ALWAYS consult the manufacturer for their recommended testing and the rating of the appliance being tested.
• Air trapped in appliances represents greater stored energy potential, and if not bled can cause a more catastrophic failure if such were to occur.

Bleed the air from each discharge at idle before pressurizing the valve.  With the pump discharge barely opened, a small stream of water is all that should be exiting when you crack the valves.  Once you close the valves on the appliance, the water pressure inside the appliance will increase slowly as the low volume of water from the discharge comes up to pressure.

The relief dump valve has opened properly here.  Take note that on manifolds such as this, the relief valve only protects the appliance with the valves in the closed position when it is used as a DISCHARGE manifold (Supplied from the single inlet side), not in reverse, being fed by several lines.  Also, note the allen wrench in the relief valve set screw used to adjust through its range.

Test the air bleeder on intake valves.  Bleed the air out at idle before pressurizing the valve.

If you test the appliance connected to the rig, do not connect it to the same side as the operators panel where you will be standing.

Many newer apparatus have intake relief valves which must be periodically tested/adjusted as well.  In this photo, the relief valve is to the right, attached to the bronze port on the butterfly valve body.  The relief dump opening is seen underneath it, as a threaded port facing downward.

Built in intake valves often have their own individual relieve valves.  Hale Master Intake and Waterous Monarch, to name two, will likely have these.  They must be tested according to the manufacturers specifications, which will require water being pumped to the intakes from another rig or a testing pump.  In addition, many pumps will have an additional relief valve attached to the suction/intake side of the pump. which needs to be tested.

Whether you test these valves in house, or have a vendor perform the testing, it is critical to have it done at the manufacturer recommended intervals and to follow their procedures.