Mike Williamson 198 Report post Posted October 11, 2003 In looking at the specs for my pump, I have a couple questions. The pump is made by Interpump, from Italy, and the model number is WS202. The specs on the pump are metric, and show it to be 21 litres per minute, and 200 bar. The conversions I have are litres/3.79=gallons, which gives me 5.5 gallons per minute, and bar*14.5=psi, which gives me 2900psi. Are these conversions correct? If so, I'm short 100psi from what the machine was advertised as (I bought it used). The 2nd issue I have is the gpm...The machine was advertised at 5.5 gpm, and my numbers back that up. However, I'm only pulling just a hair under 5 gallons. I've checked my connections between the tank and the pump, and I have no leaks. I haven't hooked the supply hose up directly to the pump yet, that's my next step. My question is, what are the possible causes of a loss of gpm, other than the engine/pump running slower than they should. Last question, how can I check that the engine/pump are turning at the proper speed? Thanks! Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted October 11, 2003 Mike, It has been my experience that the manufactors base their specs on theory, rather than actual field use. They rate the gpm and pressure at the pump, without hoses, wands, nozzles, swivels on the reel and so on. You can check engine rpm with a tachometer. You can get them for around $35.00 and they are very simple to hook up. As far as checking pump rpm, I do not know that one. Share this post Link to post Share on other sites
R. Williamson 14 Report post Posted October 12, 2003 Mike, Alan is rite . First check your engine RPM. I did the math on the conversion that pump is rated at almost 5.5 GPM. Your multiplier is 0.2641721 for that conversion. If your RPM is correct then check your pulley sizes. Just because the pump will put out those numbers does not mean that the manufacturer of the system set it up that way. Your pulley sizes should be one of the two following combinations to achieve max. pump performance. 7.75" pump & 3.35" engine or 8.75" pump & 3.75 engine. I believe these would be the most comman combinations but I reserve the rite to be wrong. Robert Share this post Link to post Share on other sites
R. Williamson 14 Report post Posted October 12, 2003 Mike, Ignore the previous post if your machine is a gear box drive and just check the engine RPM. If everything checks out we can get into what the problem may be then. Seals, valves, unloader or nozzle size. Hope this helps. Robert Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted October 12, 2003 Thanks, guys! First step is to feed the pump directly from a water supply I know is putting out at least 6gpm, bypassing the tank. That will answer if I have any leaks in the plumbing that are sucking air. If I'm still losing gpm, I'll get a tach and hook that up to the engine. If the engine is turning as it should, I'll check the pully sizes and make sure I'm running the pump at 1450 rpm (what it is intended to be run at). If all that checks out, I have to assume I have some internal problems with the pump, and we'll deal with that. Here's another question...what would happen if I put a slightly larger pulley on the pump, enough to give me, say, 6 gpm and whatever corresponding psi? I realize the pump is designed to give X psi and Y gpm at Z rpm, but if the rpm was increased, say, 20%, that should give me 6.6gpm and 3480 psi...Would this damage the pump, and if so, why? Share this post Link to post Share on other sites
Paul B. 523 Report post Posted October 12, 2003 Remember that a 100 psi deviation is 3.3% of the specified rpm. Also remember that a motor will run slower under load than without a load (as in having a pump attached). I would check the pulleys first (calculate at pitch diameters) and save the cost of the tach. for the second round. Check both the engine and pump rpm's. Check your belt - if it's a v-belt, it could be worn enough to give you a speed difference. As for increasing the speed for the pump: if it was a CAT, I wouldn't think about it twice, as the safety factor is there. Without knowing the design perimeters of the Italian pump, it's hard to tell, but having spent over 25 years in design engineering, I would guess that you should be OK increasing the rpm. There are a bunch of things that go into the design perimeters such as: - Bearing size / speeds - Heat generated / dissipated - Seal sizes / materials - Rod size / shape - Balancing Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted October 13, 2003 Will do...I'll check the pulleys tomorrow. The belts are in new condition, no wear/cracks. So you're saying that the pump could be turning at around 1400rpm and would give me the 100 psi drop? Another issue that I've noticed today. I have the flow type unloader, and normally when the gun is closed the pressure in the pump drops to zero. However, today I noticed a few times that the pump is showing around 250 psi with the gun closed, no leaks in the hoses or gun. What made me notice this is I kept hearing the engine kicking in as it does when I pull the trigger/open the ball valve...but only for a second. Is this a sign of problems with the unloader? I have a spare, and if so, I may change it out and see if that changes anything. Does anyone know of an online how-to source for troubleshooting/repairing engine/pump/burner problems? I'm pretty good with tools and fixing things, but this is a whole new animal to me...... thanks for all the help! Share this post Link to post Share on other sites
Rick G 14 Report post Posted October 13, 2003 I have a comet pump. I went to their web site and found step-by-step instructions and pictures on rebuilding. Maybe your pump builder offers the same? Rick G Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted October 13, 2003 Mike, I had the same problems with my flow unloader and the cause was a slightly leaking gun. There may be other causes, but I say that you need to check everything for a leak, as even a very little one will do this. Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted October 13, 2003 Alan: I'll check it tomorrow. I have a few spare guns, so I'll swap with one of the new ones and see if that changes anything. Thanks! Share this post Link to post Share on other sites
Michael 14 Report post Posted October 13, 2003 The PSI rating of any pump is based on the ability of the weakest component of the pump to withstand the pressure over a given time without failing. In other words it is the ability of the pump to resist the forces of the pressure. Where does the pressure come from? I will get to that in a moment. Every piston or wobble plate pump is a positive displacment system. Every stroke of the piston will displace the same amount of water. RPM will determne how many of these units of volume will be pumped. Engineers determine the safe effective working parameters for all of the moving components based on longevity of the components and their ability to withstand the stresses imposed by moving an incompressible fluid. Essentially what you have is a hydraulic pump. All pumps are rated at a set RPM to provide rated GPM/Litres. They also allow for a +/- of 10% minimum and still considered within specification. They are also rated without a nozzle in place. Now where does the pressure come from? Have you ever put your thumb over the end of your garden hose to get more power? Well, the tip provided by the manufacturer is nothing more than a piece of hardened steel with a very precise hole in the end to provide resistance to flow, therefore increasing the pressure. Using a soap nozzle will demonstrate the pressure lowering available from a larger orifice. The nozzle chart will show you what your 'actual' GPM and pressure are for a given orifice. Refer to the excellent chart here http://www.arnorthamerica.com/spraynozzlechart.html to see what the different sizes will give. Over-speeding a pump will lower it's life expectancy and void all warranties. For future conversion reference please use the following formulae... 1 bar = 14.5038 PSI 1 litre = 0.264 US Liquid gallons 1 US Liquid gallon = 3.7854 litres Hope this helps? Cheers. Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted October 13, 2003 Thanks, Michael! Share this post Link to post Share on other sites
PLD 14 Report post Posted April 2, 2006 Old thread, new questions. First some background. I have the same pump as Mike on an APW skid. I checked the net today, and the Interpump WS202 (equiv general TS2021) is rated at 3000/5.5. Q1: According to several sites (landa, hotsy) it is rec'd for use with a 11.3hp engine. My math says 15hp. Why the discrepancy? Q2: My system is equipped with an 18hp engine, and my gauge reads 3500lbs. 5.5x3500 = 17.5hp. Makes sense. But why would you put an 18hp engine on a 3000/5.5 or conversely a 3000/5.5 on an 18hp engine? FYI http://www.hotsy.com/docs/catalog/Pumps_Kits.pdf Share this post Link to post Share on other sites
Doug T 19 Report post Posted April 2, 2006 Two things come to my mind right a way. 1 if you have 115 sytem you need a few HP to drive the generator. So I assume the mfg will not use all of the pumps capabilities and have the HP necessary do drive both pump and gen. 2 if 5.5,3500 needs 17.5 HP to run at max, would you want it running at max all the time? Why not run it at 80 or 90 % and get better life out of it. Doug BTW, the general 2006 catalog rates the TS2021 pump: 5.6gpm, 3500psi @1450rpm Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted April 2, 2006 The generator came to mind with me as well. Figure on 1hp per 500 watts of generator power. Share this post Link to post Share on other sites
PLD 14 Report post Posted April 2, 2006 The parasitic drains are a good thought. I'll look into additional lossy components. For electric, I have a tiny 12v generator. Actual output unknown but I would doubt that it is 500w as that would equate to 40-50A output. Perhaps 60-100W As for the pump, it is definitely a WS202. I posted TS2021 because lamda and hotsy list the WS202 and TS2021 as equivalents. They also list both at 3000/5.6 Obviously that's not exactly correct. I just checked interpump, and they call it 5.6/2900 As for partially loading the engine, constant velocity engines like ours are different than a variable output engine like a car engine. 18hp is not "max". It's the nominal output under normal usage conditions. i.e. the engine is designed to run for years continuously at 3600rpm/18hp output. It's design max is probably more like 22hp/4500 rpm. To compare your pump engine to a car engine, think of running your car at 2500rpm/45mph and not 4500rpm/85mph. Two things come to my mind right a way. 1 if you have 115 sytem you need a few HP to drive the generator. So I assume the mfg will not use all of the pumps capabilities and have the HP necessary do drive both pump and gen. 2 if 5.5,3500 needs 17.5 HP to run at max, would you want it running at max all the time? Why not run it at 80 or 90 % and get better life out of it.Doug BTW, the general 2006 catalog rates the TS2021 pump: 5.6gpm, 3500psi @1450rpm Share this post Link to post Share on other sites
PLD 14 Report post Posted April 2, 2006 I found this pump FAQ and thought someone else might find it useful: http://www.interpump.com.au/faqs/ Share this post Link to post Share on other sites
Doug T 19 Report post Posted April 3, 2006 I was not clear in what I posted. I was not comparing the engine to car engine. I was referring to the pump running at some % less than max. Doug Share this post Link to post Share on other sites
