Tank water and a direct drive unit

[RRTServices 14]

I have a direct drive unit (3800 psi, 4 gpm) that I want to use mobile for some side work. The owners manual has in big bold print that it must have 5GPM at at least 20PSI.

Should I not even bother with trying to draw water from the tank and go right with a positive pressure setup like a Flojet On-Demand Pump 4.9 GPM, 12 Volt, 3/4in., Model# 04300143A | 12 Volt Pumps | Northern Tool + Equipment

I have searched on this topic and it seems to go both ways.

[814jeffw 71]

I can run a direct drive 5 GPM pump with 100 gallon tank,...with the outlet actually mounted a little lower than the pump. I also have an extra 200 gallon tank I can draw from, but was just pointing out that it will run off the 100 gallon tank just fine.

Jeff

[plainpainter 217]

my 3800psi,4gpm direct drive machine draws from a 35 gallon buffer tank and the supply is 6 inches below the entrance into the pump - have no problems.

[ERADicator 14]

Just about every day, I learn something good from this forum. :cool:

So while we're on the subject of tanks, can ya stand a coupl'a noob questions?

I'm guessing a belt-drive washer would be just fine from a tank, assuming no obstructions in the supply hose, etc. Is that correct?

Something I found from Hotsy when Googling around said that direct-drive washers are better off when fed from a pressurized source because the pump is constantly spinning at 1725 or 3450 RPM, or whatever the motor's revolutions are.

When I worked at the local rental center a few years ago, customers often returned electric pwashers with complaints that "it won't work." When the manager drove out to see if he could figure out their problem, some of the time it was because of a bad electrical hookup (GFCI vs. GFCI, or too small an extension cord). The rest of the time, it was because their well pump/pressure tank wouldn't keep up with the water demand.

And I'll bet the pump would cavitate long before it started to collapse a tank, but would it be a good idea to take the cover off an "IBC" before starting the washer? I don't know if/how those are vented, but I figure that letting air get in unobstructed might not be a bad idea. Sound right?

I just bought a 250-gallon IBC, plumbed with a 2" ball valve. That should feed a washer pretty well, eh?

Thanks for input.

[4000psi 16]

My 5.2gpm 3000psi draws from a 325gl tank never been a problem even with the pump above the outlet.

[schrec 64]

You need the water level in the tank to be higher than the pump inlet.

[FullBlast 14]

Some pumps are desiged to pull some are not.

The belt drive are more commonly known to pull water on their own but not all of them will either.

I was changing pumps on my one trailer and they sent me the wrong pump, I forget what the specs were on it, 8 at 3500, I went ahead and put it on but couldn't get that thing to suck to save my life. Sent it back and got the other model that looked just like it and it worked great.

If they are a good sucking pump they will lift water from below.

I have 7 pumps that are set up to pull out of tanks.

As far as putting a 12v pump in front of it to pressurize it??? Man I'm not sure about that. I'm not saying that won't work, I just got my ?????? about it.

[4000psi 16]

the water level is usually below the pump when I start a job and it still pulls up no prob.

[kcpowerclean 14]

the water level is usually below the pump when I start a job and it still pulls up no prob.

Does the water start to draw when the machine fires up or do you need to prime it somehow?

[Paul Kassander 26]

If there are no air pockets it will draw right away and pull up. If you have air in the line you may need to get the pump below the water level to get it to prime and suck the water.