I have a question about the hoseline layout for conducting an annual pump test. We are using an Akron test kit and a portable ground monitor that has (3) 2.5" inlets. The issue we have is on the 1250 and 1500 GPM tests. Up to 1000 GPM, the Akron hose layout sheet listed (3) 100' lines (2.5" hose) when conducting the 100% capacity test. Well, when you get to the 1250 and 1500 GPM pumps, it adds (1) 50' line in addition to the (3) 100' lines for the 100% capacity test.
Like I said, our monitor only has 3 inlets. I called Akron, and the tech support guy wasn't sure about the answer and had to research some. He called me back and said that the additional 50' line was to "control" the friction loss when pumping the additional volume of the 1250 and 1500 pumps. His suggestion was to substitute (1) 50' line in place of (1) 100' line. So, the layout would look like this:
1250 GPM @ 150 PSI = (2) 100' lines and (1) 50' line
875 GPM @ 200 PSI = (3) 100' lines
625 GPM @ 250 PSI = (2) 100' lines
The hoselines for the 200 and 250 psi test are unchanged from the chart. Basically, for the 150 psi test, he said to drop down to 50' on one line to see if that will give the desired flow at the correct pump pressure. He said if it doesn't, drop an additional line down to 50'.
Is this the correct way of doing it to still produce an accurate test result? From what I have read and seen other people do, this appears that it would. By using the shorter sections, friction loss would be diminished, and you would have to gate down the discharges a little more, perhaps, to achieve the correct numbers.
What layout would you all suggest with only 3 monitor inlets to work with?
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12-10-2012, 10:15 PM #1
- Join Date
- Jan 2008
Hoseline layout for annual pump test
12-21-2012, 07:20 PM #2
- Join Date
- Mar 2003
You will proably have to use 3" on the 1250 deff on the 1500 test. Also make sure your monitor will flow 1500 . I have a huge sam eastman circa 1930s with a massive waterway. With 3" I use three 100 ft sections and of course gate down on the 70% and the 50% tests.?
12-24-2012, 03:02 PM #3
- Join Date
- Nov 2007
Most of this depends on how much friction loss you need to get the correct pitot pressure reading for the tip being used. If you are performing a 150 PSI test and need 100+ at the tip, you need less friction loss. If you need 70 PSI at the tip you need the friction loss. Of course, you can always set up the most efficient hose lay and gate your discharges to raise engine pressure and still get the drop at the tip.
As long as the master stream appliance can handle the flows, multiple lines can be siamesed into the inlets. Back in the day pump tests were performed with 100' of 2-1/2" hose for each 250 GPM of flow. Thus, a 1500 GPM test would have been done with six individual lays into a single master stream or multiple devices.
Personally, I am a big fan of 3" hose for annual testing. Less setup and take down time.
12-25-2012, 09:13 PM #4
- Join Date
- Jan 2007
- Pa Wilds
CFD508: After reading your post, I think I'm detecting a certain degree of unfamiliarity with hydraulics. First, it is not possible to perform the 1500 gpm test with a 2 inch tip, and you have not stated the size of the tip on the portable monitor. You will need at least a 2.250" tip to perform the 1500 gpm test using only one nozzle. Yes, the Akron Tech is correct in suggesting one or more lines of 2 1/2 be only 50 feet long. You can not achieve the exact friction loss in the hose alone, without gating one or more discharges back to add friction loss from the engine to the monitor. You will need a pitot pressure of 98 psi on the 2 1/4" tip to achieve 1500 gpm. This leaves 52 psi to overcome the friction loss between the truck discharge and the monitor. Frequently monitors have an internal loss of around 20 psi, and we should expect about 10 psi loss between the pump manifold and the hose connection on the engine. This leaves only 22 psi for friction loss in the hose line. The flow will divide roughly into 3 equal flows, or 500 gpm in each line. A good estimator for friction in 2 1/2" hose is (flow/100) squared times 2 or about 50 psi per 100 ft. of hose. Thus the use of only 50 ft. lines from the pump to the monitor may still provide too much loss (25 psi). firepundit was absolutely correct in suggesting 3" line when performing this test. Having too little friction loss in the layout is not a problem since adding more friction loss is simply a matter of gating one or more valves back slightly to add more loss between the pump and the nozzle. If you must use a 2" tip on the monitor, simply connect a 1 1/8" nozzle to a discharge, throttle the engine to 150 psi and gate back this valve until you find the pitot reading 65 psi (304 gpm) Next, slowly open the lines to the monitor and increase the throttle to maintain the 150 psi engine pressure while having an assistant check the nozzle pressure on monitor until you achieve 100 psi on the pitot, with the engine operating at 150 psi. You will now be flowing a total of 1500 gpm. Remember to lock the valves after setting the correct pressures. High flows through valves have a tendency to suck the valve shut causing teriffic water hammers.
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