I meant to mention Tier 3's, not a lot of experience on the new ones as yet and nothing a year down the road and so on.. Should be interesting. >From what I know, bench drivers are only used on HSC electrics and verticals with motors. I posted about this once. Look at the 'certified' curve and see if the new pump was tested with a shop driver (adjustable for BHP and speed) or the actual driver that came bolted to it. I haven't seen too many engine driven pump done at the factory with other than the designed engine. Sometimes, in expediting the pump, the factory will use one of their adjustable drives and pump from the break tank to get a curve done and out to the salesman, mostly motor driven units. I don't think I'm giving away any secrets here, they all do it. I will say on start-up of an engine driven unit, I always have the engine guy (or me) back off the governor and set it to PUMP nameplate requirements at 150%, tested like I posted before. It's the pump that sets the requirement and the driver is matched (sometimes not too well) to its needs. Hope this helps. Tom
Can any of the pump manufacturers weigh in on this issue, and elaborate a little on the future availability of a PLD on a Tier III? Mark at Aero It's not as easy to retrofit one on a Tier III as it first seemed...... That was the beauty of the PLD's. We could size the pump to compensate for the mandatory de-rating of the supply and buy back the pressure without going over 175 psi. Ron Fletcher Not doing pumps on a regular basis, I may be missing something but your required to compare the actual performance with the "Certified" pump curve. Now we always received the certified curve with the pump, and there were minor diviations from the Cat. Curves. So I would say that if your design meets the "Certified" curve performance your OK. Using any "Actual" performance above that curve would be iffy, as you'd have to prove it's not based upon a varied supply or other factor. Example: Static 50 Residual 20 @ 1750, but the engineer requires that you only use 45/2...@1575 for future supply degrading. You should exceed the design when you run your pump test, but if you try and use that, you'll negate the safety factor the ERO was building in. Thom For a retrofit you wouldn't do a pump test and then use the results of the test for the calculations? Ron Fletcher I would contact the mfr. The listing is based on their data sheets i believe. So the calcs are based on the listed, approved pump. Forest Sent from my Verizon Wireless Phone Sent from my Verizon Wireless Phone ----- Reply message ----- From: "Tom Duross" <[email protected]> Date: Tue, Aug 31, 2010 8:09 pm Subject: Diesel Pump Engine RPM To: <[email protected]> Short answer, yes I believe. Typically, engine speed required by the pump is at 150% and climbs according to the engine as you approach no load. Engines have an operating range and usually selected and governor set for the pump's requirements. I thought there might be a disclaimer in the most recent 20 regarding PLD controllers, but not to my knowledge. I know with non-PLD controllers, we always start at 150% and work our way back when testing engine-driven pumps as that helps cool-down. Plus, you can check RPM at first flow point. It's unfortunate affinity calculations are based upon constant speed (as I understand them), which never exists regardless of driver type. Sorry for seeming vague but the books beyond arms reach. TD NFPA #20, 2003, 11.2.4.1.1. "Engines shall be provided with a governor capable of regulating engine speed within a range of 10 percent between shutoff and maximum load condition of the pump." Does this mean that a 1760 rpm rated engine running at 1860 rpm is acceptable? If a 1760 rpm rated pump when tested produced 1860 rpm (less than 10%) can the pressure produced at the higher rpm be used for the system calculations? In other words can the actual pump test be used for the system calc's or must we use the manufacturers data sheet regardless the test results? The pump is a PLD if that matters. Ron Fletcher _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
