Original article → An Inside Look at Pump Testing
By Author(s): Allan Burnham
Published June 1st, 2010 at Fire Research
In most communities the first truck out the door to a reported incident is an engine. These engines are equipped with pumps, hose, water and an assortment of specialized tools necessary to perform a host of emergency functions. Should a pumper be required to supply large quantities of water, it will need to hook up to a municipal hydrant system or draft from a nearby water source. To insure these pumpers perform from year to year at their rated capacity, the National Fire Protection Association (NFPA) has developed definitive pump testing standards along with step-by-step procedures on how to perform these specified tests and interpret the results. These results are then subject to review by insurance rating agencies, such as the Insurance Services Office, Inc. (ISO), a private organization that provides services to insurance companies by rating the fire suppression capability of a community. This is done on a 100 point system, of which 50 points is fire department related. All this determines the classification of the department, which can affect the insurance rates for the community.
ISO, like NFPA, requires annual pump testing to receive full credit in this area. Although in-service pump testing has been required for as long as the fire pump has been around, it’s amazing how many fire departments have never tested the fire pumps on their apparatus. Even more amazing is how many firefighters have never operated or witnessed a pumping engine at draft. Some departments have defined maintenance schedules and driver/operators perform daily and weekly operational maintenance inspections on a routine basis. However, the reality is most departments only exercise the valves and controls on these engines from one fire to the next. Unfortunately, the fire ground is not the place to be testing your pumps. Virtually every firehouse you walk into today has an engine with a pump leaking water on the floor, discharge and relief valves that won’t open or operate, primers not working, drain valves leaking, leaky or broken pressure gauges, and assorted plumbing leaks. These are all areas that need to be inspected on a periodic basis, or at the very least annually, prior to running the pump service test.
How to Get Started
Prior to performing the actual pump test, there are a number of inspections and preliminary tests that need to be conducted to verify the pump’s condition is fit to run the test. For anyone not familiar with the process of pump testing, there are several industry reference guides, manuals and standards available that provide step-by-step instructions on what to inspect and how to perform the appropriate tests.
NFPA 1911 (Standard for the Inspection, Maintenance, Testing and Retirement of In-Service Automotive Fire Apparatus, 2007 Edition) has been expanded for 2007 and now incorporates the previous NFPA 1914 (Standard for Testing Fire Department Aerial Devices) and NFPA 1915 (Standard for Fire Apparatus Preventative Maintenance Program). The International Fire Service Training Association (IFSTA) also has published a 2006 second edition of Pumping Apparatus Driver/Operator Handbook. This manual contains 16 chapters that provide an in-depth look into the responsibilities of firefighters assigned to drive and operate fire department vehicles equipped with a fire pump. Pump theory and accepted pump test methods are covered in illustrated detail along with tables, sample vehicle inspection forms and sample forms for recording the results of all tests conducted. Short of some practical experience and a few pieces of specialized test equipment, this is all you need to get started.
Although some of these inspections and tests can be conducted by qualified driver/operators, there are a few critical inspections and tests that should be performed by trained professionals with previous experience in pump testing. There are industry service centers available in just about every location across the country that test hundreds of pumps every year. They usually employ ASE and EVT certified technicians who are very capable of running any of the required tests, and in most cases supply all the specialized test equipment needed. These tests will require the apparatus to perform at maximum capacity, which it doesn’t do on a day-to-day basis. Should an unexpected condition present itself during the actual test, these technicians know what to look for, how to react quickly in correcting any encountered problems, prevent or minimize any damage, and make sure the results are properly documented for rating agencies like ISO.
There are a few essential preliminary inspections that need to be performed prior to actually running the pump test itself. NFPA 1911, Chapter 9, (Inspection and Maintenance of Water Pumping Systems and Water Tanks) gives you a good overview of the systems and components that need to be inspected, tested or adjusted prior to running the test.
- Verify that all fluids in the pump drive system, primer (if equipped) and gear case are at the proper level.
- Verify that all pump shift controls operate smoothly, that all interlock mechanisms engage properly and pilot lights are working.
- Verify that all discharge and intake valve controls operate smoothly including the transfer valve and relief valve (if equipped).
- Engage pump and inspect pump packing or mechanical seals, adjust or replace (when necessary) in accordance with manufacturer’s recommendations.
- With pump engaged, inspect plumbing and gauge lines for leaks and verify that all gauges and instruments are registering accurately. Also, verify that primer valve control and motor are functioning properly.
There are several other inspections that can be conducted and are usually performed under a complete pump service inspection. However, as long as you have performed these few simply inspections and made whatever adjustments were required, you are now ready to head to the test site.
Selecting the Test Site
(below 2000 feet elevation)
First you will need to determine if you are going to test from a pressurized water source or a static source. The more people you talk to, the more you realize everyone has their own idea about the method used for testing pumps, which in some cases can influence the decision on where the test should be conducted. Some departments and service centers use long standing in-ground test pits with 20,000 to 40,000 gallons of water. Others may use what they call portable tanks (Fold-a-tanks and Port-a-tanks). Portable tanks are quite popular and all used successfully. The problem with portable tanks is controlling the water turbulence coming back into the tank while pumping at capacity and maintaining the water temperature below 90 °F over a sustained period of time. There are also a few testing companies currently developing and experimenting with specially constructed water pump test trailers. Although these companies claim their methods offer the best solution, there are always pros and cons to every solution. All you really need to keep in mind is that its always preferable to keep the water source below the pump (from draft) whenever possible. All things being equal, this usually will produce the truest test of a pump’s capability.
However, this theory wouldn’t be true when testing from a hydrant. Yes, according to NFPA, pump testing from a hydrant is permitted. Just make sure you select an area that provides ample space for discharging the water, and verify the hydrant is capable of flowing the rated capacity of the pump. Also remember, when testing from a hydrant you must add the static pressure of the hydrant to the net pump pressure. For example; when you open the hydrant and realize a static pressure of 70 PSI, this means when running the capacity test at a rated pressure of 150 PSI, the net pump pressure would now be 220 PSI. This is all well and good until you get to the 50% test. With a rated pressure of 250 PSI the net pump pressure would now become 320 PSI. At this pressure you start to approach the rated capacity of the plumbing and any weak links start to give way, like pipe plugs, corroded pipe threads, tubing and fittings, etc.
Set-up and Preparation
Setting up for the actual test takes a little forethought to be sure the apparatus is positioned to maximize the length of the suction and discharge lines. Depending on how the site sets up, it’s preferable to keep the operator’s panel on the opposite side from the suction hose whenever possible. You also need to be close enough to the water source to prevent having more than 20 feet of suction hose above the surface of the water. If you are using a natural water source, it usually helps to place a 14 or 16 foot roof ladder under the suction hose to provide support and keep it elevated off the bottom of the water source. You will need to attach an appropriately sized strainer at the end of the suction hose and strap it off to the ladder as well. Floating strainers can be used, but must be submerged at least 2 feet below the surface. (Appropriately sized strainers should have 2 to 3 times the open area of the suction hose being used.)
When attaching the suction hose to the pump you should use the side inlets whenever possible. Front suctions and rear intakes should be avoided as they usually are too restrictive to achieve adequate flow. It’s also necessary to remove any suction or piston intake valves prior to hooking up the suction hose. These valves also are too restrictive and will not allow you to reach full capacity. Tables contained in NFPA 1911, Chapter 18, provide you with all the suction hose requirements for size, number and maximum lift depending on the size pump you are testing.
Once you go to 1500 gallons, the table indicates you need to use two (2) 6 inch suction hoses. Typical set-ups are seen with a 6 inch suction hose off each side. In most cases this is just not practical where the second hose usually has to run under the truck. There are companies using a specialized 6 inch wye manufactured by Kochek Company of Putnam, CT with two (2) 6 inch suction inlets that allow two (2) suction hoses to be connected off one side.
Test data shows that the vacuum required in this case is cut in half. As a reference, when your vacuum approaches 15 inches mercury, you will start to lose pump pressure and will be forced to abandon the test. Remember, the whole secret to running a successful pump test is getting enough water into the pump.
Determining what to use for a discharge appliance can result in several options. Basically, there are only two (2) types of appliances capable of handling the heavy water streams associated with pump testing. There are portable monitors that can be set on the ground or on a fixed platform. These monitors are limited in the fact that most are only rated at 1250 GPM. There are also high capacity fixed monitors that are attached to trucks and trailers equipped with high capacity flow meter tubes, pitot gauges and a number of interchangeable smooth bore tips.
Permanently affixed “deck guns” also can be used. If you intend to use the pre-piped deck gun on the truck, it’s helpful to determine the rated capacity of the gun. Remember most monitors being mounted on engines today are demountable for portable operation and are rated only for 1250 GPM. Due to the manufacturer’s rating, caution should be exercised whenever these appliances are used above 1250 GPM. Although, certain type monitors probably will flow higher capacities than they are rated for, serious vibration will be encountered which can raise several safety concerns and equipment damage. Testing pumps in excess of 1250 GPM will require a larger rated monitor or setting up an additional monitor where water flows can be captured from both monitors and added together. Getting water to these appliances is usually accomplished with appropriately sized discharge hoses. Any combination of 2-1/2, 3 or 4 inch hose in 50 foot lengths will move enough water to allow you to test pumps up to 2000 GPM. The last thing you need to hook up is an independent set of calibrated test gauges which thread into tests ports on the pump panel. Remember, these gauges need to be calibrated within 60 days preceding the test. It’s also helpful to have an RPM counter (when connections are available) to verify engine RPM within 50 RPM.
Performing the Test
With the hook-up complete, there are a few last minute considerations prior to actually flowing water. With the truck properly chalked, start the engine and engage the pump. Prior to engaging the primer, verify the pressure relief valve (on non-electronic engines) is set above 250 PSI so as not to restrict the pump’s ability to reach capacity. On electronic engines, select the RPM mode on the engine governor control panel so the throttle can be advanced manually.
If the truck has a 2-stage pump, you will need to verify that the transfer valve is in the proper mode (volume or pressure) and make sure all discharge and drain valves are closed. Locate the pump manufacturer’s test plate (usually somewhere on the pump panel). Make a mental note of the engine RPM for the particular test your running. Once the test is started and you have reached the proper pump and nozzle pressure, you want to make note of the engine RPM, which should not be more than 100 RPM higher than the original test plate reading.
The first test you’ll be running is the 100% capacity test. The net pump pressure you want to achieve for this test is 150 PSI. As an example, we’ll assume the pump is a 1000 GPM 2 stage pump. According to the flow chart table listed in NFPA 1911, the smooth bore nozzle on the discharge monitor would have to be 2 inches in diameter. At a nozzle pressure of 72 PSI and a net pump pressure of 150 PSI you will be flowing water at a rate of 1008 GPM. Now open the tank-to-pump valve for a few seconds until you see water bubbling up from the inlet strainer and then close the valve. This will flood the suction hose and flush any debris out of the strainer that may have collected during the hook-up. Now raise the throttle to around 1000 RPM and pull the primer control. This is an area where methods may differ on whether to raise the throttle or not. Some people like to prime the pump with the engine speed at idle. Either method is acceptable as long as you can stay within the priming time standard. You should time this function and record it on the pump test record sheet. Within a matter of 30 to 45 seconds, depending on the size of the pump, all the air should have been exhausted and replaced with water. You should have noticed the vacuum gauge reading going up as well as the pressure gauge reading. Slowly open the first discharge line (in the case of 2) to the monitor and let the water pressure stabilize. Then open the second line. Now advance the throttle until you reach 150 PSI on the test gauge. Verify the nozzle pressure of 72 PSI or the flow rate of 1000 GPM by use of the in line pitot gauge or a flowmeter.
If the nozzle pressure reading is too high, you may not even need the second line. Once you’ve reached the correct pressures you want to verify the engine RPM is not over the plate reading by more than 10 percent. With everything in limits, you need to run this test for 20 min. At the end of this test you can run the overload test, which is nothing more than raising the net pump pressure to 165 PSI and holding it there for 5 minutes.
The next test is at 70% of capacity, which is 700 gallons a minute. You’ll only need one discharge line for this test, and will need to change the nozzle to 1-3/4″ reduce the throttle back to idle and close the discharge valves. Change the nozzle, open the discharge line and ramp the throttle back up. You should be able to accomplish this without losing your prime. This test is run at 200 PSI net pump pressure at a nozzle pressure of 60 PSI. The difference with this test is you have the choice to run the test in either volume or pressure. Most test plates on the pump panel say either/or. The general rule of thumb here is anytime you are running a pump at better than 50% capacity, you should be in volume. This theory is also being taught at most state firefighter academies. In order to reach 200 PSI net pump pressure without exceeding the 60 PSI nozzle pressure, you will have to gate back the discharge line. Run your throttle up to about 150 PSI and then gate the discharge line back until you reach the 200 PSI. Now verify the reading on the pitot gauge is at 60 PSI and the engine RPM’s are within limits. You will only need to run this test for 10 minutes.
The final test is at 50% of capacity, which is 500 gallons a minute. Again you’ll only need one discharge line for this test, and you will need to change the nozzle to 1-1/2″.
Follow the same procedure as the 70% test except this test is run at 250 PSI net pump pressure at a nozzle pressure of 60 PSI. The only other difference in this test, in the case of a 2 stage pump is to move the transfer valve to the pressure mode. This test is also only runs for 10 minutes.
Now that you’ve completed the last test, as you decrease the throttle stop at 150 PSI and reset the pressure relief valve if equipped.
It’s important to remember that suction and discharge valves should always be opened and closed slowly to avoid water hammer and possible pump damage. The throttle also should be advanced and decreased slowly as well to avoid any unintentional shock, and allow any entrained air to dissipate.
Hopefully this has cleared up some myths about pump testing and has provided you with a little more information on the need for conducting annual pump tests.
Consultant & Master Technician
Fire & Emergency Maintenance Co. LLC