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GOT
BY GEORGE LANTHIER
designed to do and ‘ operate ’. But when you start to add ‘ lift ’ or vacuum to the pump it starts to ‘ work ’.
Let ’ s go back to the heart analogy again . You ’ re sitting there reading this and your heart is just operating as designed . You get up and start walking around and your heart starts beating faster . You now start jogging and maybe even running , is your heart beating as it was when you were just sitting there ? Of course not , now it ’ s not only ‘ operating ’ but it ’ s ‘ working ’, big time ! That ’ s what happens when we ask a pump to operate under vacuum , we put it to work . And don ’ t forget the pump
Figure 7
Figure 8 only works when it ’ s under vacuum or a restriction , kind of like a blocked artery . Put enough restriction on that pump and you get a ‘ heart attack ’ and you ’ re in deep trouble . With all of this in mind let ’ s look at the typical problem .
In Figure 3 we see a diagram of two pumps and a tank . We ’ ve removed all the distractions and other ‘ trees in the forest ’ and only have a clear view of these two . We ’ ll go on to further define the job as one which has a furnace on the left and a water heater ( or boiler ) on the right . Can you see the problem ? If you can ’ t you ’ re in trouble right off the bat , it ’ s the height ! That lower pump on the right is never going to have a problem as long as you have a good quality , clean fuel coming to it , it ’ s ‘ gravity fed ’ in its purest form . But what about the higher pump ? What happens when the fuel level in the tank goes below the pump shaft on the higher ( left ) pump ? And , would the lower ( right ) pump attempt to drain the upper pump at that point ? The answer is that yes , the lower pump would pull the oil from the upper pump because we not only have ‘ height ’ to contend with we have haven ’ t taken into account the other equation to vacuum , ‘ length ’.
When we determine the ‘ calculated vacuum ’ of a pump we should know that under vacuum a working single-stage pump can only lift oil under six inches of vacuum ( Hg ) on a one-pipe system and no more than 11 inches successfully on a twopipe system . We also know that our pumps can operate within a ‘ calculated vacuum ’ of one inch per one foot of lift and one inch of vacuum per 10 feet of horizontal run . Let ’ s look at a couple of working examples for a one-pipe system .
In Figure 4 we show the ‘ lift ’ as four feet , so that becomes four inches of vacuum and the ‘ run ’ as 20 feet that becomes two more inches of vacuum . But if we change the ‘ lift ’ to two feet , that becomes two inches of vacuum and the ‘ run ’ as 40 feet that becomes four more inches of vacuum . So , in both examples we have maxed out our pump at six inches of vacuum , but what about valves , fittings , filters etc .?
Well , you don ’ t have to worry about that with the current pumps out there because although we still calculate vacuum ‘ old school ’ the good news is we have a built in ‘ fudge factor ’. The one vs one rule applied to older pumps like the Suntec J , Figure 5 , but the smaller , high-speed pumps , Figure 6 , only use ¾ inches of ‘ operating ’ or ‘ gauge vacuum ’. When we multiply six times ¾ inch we end up with only about four and one-half inches of ‘ working vacuum ’ (. 75 inch x 6 = 4.5 inches ) and with that ‘ fudge factor ’ you don ’ t have to worry about your fittings but always use and trust an accurate gauge . Are you starting to see the problem from Figure 4 now ? We not only have to deal with the height differences but also how far then oil has to travel keeping one of the most important Rules of troubleshooting to remember , ‘ everything , absolutely everything takes the path of least resistance ’. So back to how to fix the
more difficult of the ‘ two pump , one line ’ problems , the one with the lift .
This is the tougher of the two examples because of that ‘ height ’ consideration again . But to make it work it ’ s basically just a matter of building some loops around the two pumps , Figure 7 , I call it ‘ Lindy ’ s Loop ’, ( for Lindy Lindveit ). You may be sitting there also saying that by the time I do this I can run a second line ! You won ’ t get a fight from me on that one and maybe that was Lindy ’ s idea too . Again , we left off the valves and filters for clarity , but I ’ d put a decent filter at the tank outlet and a good spin-on at each burner . And yes , both pumps must have the by-pass screw installed for this application and no damned check valves please .
The easier one is the gravity job , Figure 8 . With two pumps at pretty much the same level you just have to use one to go through to the other . No by-pass plug in the first pump since there is no return to the tank and that ’ s it .
So now you know how to make these jobs work and hopefully it will make your life easier . Thanks for reading this and see ya ! l FON George Lanthier is the owner of Firedragon Academy . His website can be found at www . FiredragonEnt . com which includes a link to Firedragon Academy ’ s Facebook page .
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36 FEBRUARY 2023 | FUEL OIL NEWS | www . fueloilnews . com