810f250
Griffs Services PowerWash
This is a response to a question from another thread. I think this info maybe helpful to others.
http://www.propowerwash.com/board/upload/showthread.php?t=17377&page=3
This is what I have come up with, I have a TSF2021 at ~1750 rpm , head pressure set at 3600 psi with new 8.5 tip trapped pressure unloader, at that rpm it should be outputting ~8.5 gpm I am running 3 of 1503 nozzles in the SC, which would be equivalent to a single 1509 nozzle in the lance. Using the barnes nozzle calculator backward, it will can calculate any unknown number form two inputs.
So with a 8.5 new tip and the my trigger open, I slowly tightened the trapped pressure unloader looking at the gage and the flow back to the tank. It just so happened at 3600 psi head pressure there was no flow in bypass back to the tank.
Used the barnes calculator and determined my pump flow. (I want to get a stroboscope to determine the exact pump speed to ensure I am not over speeding the pump or engine. (i have put a tiny tack on the engine and measured the pulleys and tune to what seems to be 1750 rpm pump input, but the stroboscope would be the best test)
anyway, the flow could be calculated by inputting the nozzle size 8.5 and the pressure at which the bypass flow stopped, which happened to be at general pumps maximum 3600 for me (that may have been luck/coincidence) the calculator yields 8.1gpm
So assuming the barnes calculator correct (no evidence to dispute it) my pump is output is 8.1 gpm. Remember I am using 3 of 1503 tips in my 30" SC, which is equivalent to one 1509 nozzle in a lance. Using the barnes calculator again input the 8.1 and the equivalent single tip value of 9.0 for the nozzle field and the barnes calculator yields 3240psi. Which is almost what I do actually see on the head when running my surface cleaner (gage reads 3200psi).
So I could reduce the nozzle sizes in the Surface cleaner to get the full 3600 psi head pressure, but the next size down from 1503 is 1502.5,
so 3 1502.5 nozzles is equivalent to one 1507.5 nozzle, if I did that the pressure would jump to 4666psi, if I dont have an unloader and the engine has the HP capacity, but the unloader would/should open at 3600 psi and the remaining flow routed back to the tank. (using the calculator to get the flow input 3600 psi and 7.5 for the nozzle and press calculate, you would get 7.1 gpm that means (8.1-7.1)=1 gpm is routed to the tank).
Sound all well an good but is it advantageous? I get 400 more psi on the head but is there an increase in cleaning impact?
Theoretical Impact= K x flow x sq root of psi
where "K" is a constant but i would not use its value in my calculation because i am comparing impacts not actually looking for the numerical value.
Note:when using different nozzle degrees the theory impact is reduced as the nozzle angle is increased, but again I am comparing to sets of 15 deg's , I am only varying the orifice size, namely 1503's and 1502.5 so the % of theory impact is also a constant.
Setup one , for 3 1503's nozzles in SC with 3200psi head pressure:
Total Theory Impact is = 8.1 x sq. root (3200) = 458.2
Setup two, for 3 1502.5's nozzles in SC 3600psi head pressure:
Total Theory Impact is = 7.1 x sq root (3600) = 426
As you see although the pressure is 400 psi less the potential cleaning impact from setup one yield the highest cleaning forces.
(the maximum potential system theory impact is 8.1 x sq root (3600) = 486 )
The advantage of setup two is the potential heat rise derived from running 1 gpm less though the coil and if impact is not as critical (setup two impact is still significant because a 5.5 gpm @ 3500psi machine Theory impact is = 325.4 and a 5.5gpm machine still cleans great.)
I have heard many say that running a trapped pressure unloader continuously with water through the bypass will wear it out prematurely. It maybe wise to use a suited regulating valve.
http://www.propowerwash.com/board/upload/showthread.php?t=17377&page=3
Nigel, wont that be creating too much back pressure and wear your seals out faster?
Wont it also get less water on the surface and reduce cleaning speed? what SC are you runnung?
This is what I have come up with, I have a TSF2021 at ~1750 rpm , head pressure set at 3600 psi with new 8.5 tip trapped pressure unloader, at that rpm it should be outputting ~8.5 gpm I am running 3 of 1503 nozzles in the SC, which would be equivalent to a single 1509 nozzle in the lance. Using the barnes nozzle calculator backward, it will can calculate any unknown number form two inputs.
So with a 8.5 new tip and the my trigger open, I slowly tightened the trapped pressure unloader looking at the gage and the flow back to the tank. It just so happened at 3600 psi head pressure there was no flow in bypass back to the tank.
Used the barnes calculator and determined my pump flow. (I want to get a stroboscope to determine the exact pump speed to ensure I am not over speeding the pump or engine. (i have put a tiny tack on the engine and measured the pulleys and tune to what seems to be 1750 rpm pump input, but the stroboscope would be the best test)
anyway, the flow could be calculated by inputting the nozzle size 8.5 and the pressure at which the bypass flow stopped, which happened to be at general pumps maximum 3600 for me (that may have been luck/coincidence) the calculator yields 8.1gpm
So assuming the barnes calculator correct (no evidence to dispute it) my pump is output is 8.1 gpm. Remember I am using 3 of 1503 tips in my 30" SC, which is equivalent to one 1509 nozzle in a lance. Using the barnes calculator again input the 8.1 and the equivalent single tip value of 9.0 for the nozzle field and the barnes calculator yields 3240psi. Which is almost what I do actually see on the head when running my surface cleaner (gage reads 3200psi).
So I could reduce the nozzle sizes in the Surface cleaner to get the full 3600 psi head pressure, but the next size down from 1503 is 1502.5,
so 3 1502.5 nozzles is equivalent to one 1507.5 nozzle, if I did that the pressure would jump to 4666psi, if I dont have an unloader and the engine has the HP capacity, but the unloader would/should open at 3600 psi and the remaining flow routed back to the tank. (using the calculator to get the flow input 3600 psi and 7.5 for the nozzle and press calculate, you would get 7.1 gpm that means (8.1-7.1)=1 gpm is routed to the tank).
Sound all well an good but is it advantageous? I get 400 more psi on the head but is there an increase in cleaning impact?
Theoretical Impact= K x flow x sq root of psi
where "K" is a constant but i would not use its value in my calculation because i am comparing impacts not actually looking for the numerical value.
Note:when using different nozzle degrees the theory impact is reduced as the nozzle angle is increased, but again I am comparing to sets of 15 deg's , I am only varying the orifice size, namely 1503's and 1502.5 so the % of theory impact is also a constant.
Setup one , for 3 1503's nozzles in SC with 3200psi head pressure:
Total Theory Impact is = 8.1 x sq. root (3200) = 458.2
Setup two, for 3 1502.5's nozzles in SC 3600psi head pressure:
Total Theory Impact is = 7.1 x sq root (3600) = 426
As you see although the pressure is 400 psi less the potential cleaning impact from setup one yield the highest cleaning forces.
(the maximum potential system theory impact is 8.1 x sq root (3600) = 486 )
The advantage of setup two is the potential heat rise derived from running 1 gpm less though the coil and if impact is not as critical (setup two impact is still significant because a 5.5 gpm @ 3500psi machine Theory impact is = 325.4 and a 5.5gpm machine still cleans great.)
I have heard many say that running a trapped pressure unloader continuously with water through the bypass will wear it out prematurely. It maybe wise to use a suited regulating valve.