3000psi hydra. cyl. ok running at 2500psi ?

M

mgysgthath

Joined
Dec 15, 2009
Messages
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I'm planning my press build with the help of Baton's book, Eric and the Count, plus a few others (and all of you of course -- thanks to all!). I am sourcing parts based on Baton's build and Eric's design.. and I've got the motor and plan on getting the cylinder next, so I can plan the frame height accordingly.

Batson recommends a 5" x8" 2500psi cylinder with a 1 3/4" rod from Grainger, which is $558 US + shipping.
http://www.grainger.com/Grainger/ww...ae-8208&op=search&Ntt=sae-8208&N=0&sst=subset

Whereas Northern has a 2" shaft 3000psi cylinder for MUCH cheaper at $289.99 +ship.
http://www.northerntool.com/shop/tools/product_23518_23518

I plan on using the same pump or one with the same specifications as Batson used, which is 5.5 GPM @ 2500psi w/ 2 HP (I have the 2HP motor already). So my build will be 2500 PSI.

What I am unclear on is although the cheaper (stronger 2" rod) cylinder has a max pressure of 3000 psi, will it run as effectively (the same force) at 2500 psi, or do I need to shell out and get the more expensive one?

Merry Xmas all :P
 
It should put out the same tonnage at a lower PSI than it's rated? I wonder why Grainger is so insanely expensive..? Thanks again !
 
mgysgthath said:
It should put out the same tonnage at a lower PSI than it's rated? I wonder why Grainger is so insanely expensive..? Thanks again !
Click to expand...

I don't understand that question

Tonnage is

area of the cylinder in square inches x pressure in PSi / 2000 pounds




The 2500 or 3000 psi rating of the cylinder is just a working safety rating - the max you can use it at.

Since your pumps are 2500 psi
"I plan on using the same pump or one with the same specifications as Batson used, which is 5.5 GPM @ 2500psi w/ 2 HP (I have the 2HP motor already). So my build will be 2500 PSI. "

then with either cylinder your tonnage will be 21.6


If you want' more tonnage, increase pressure, or cylinder bore diameter.
 
Thanks guys.. Ya I suppose I wasn't clear on that, I was just concerned that it "wanted" to run at 3000psi and would put out sub-standard performance at 2500, but I thought that it should work at a lower pressure and the same output force. Thanks for confirming that.

That's still a good price Eric, as opposed to the one from Grainger.. I mean dang, what is with their prices? Anyway thanks :) I am gathering parts one at a time for now, but it shouldn't be too long until I can get to welding :D
 
As Count says, that is the maximum working pressure rating, not the required or ideal operating pressure. You have more wiggle room with the one you are asking about.
 
Hey mgysgthath!!

Just started the same press build as Eric's... Different stand and such though but close.... Your in Ontario. Me Too!!! We should keep in touch on our builds if there is anything I can help, let me know...

Dezi
 
The rating is for MAX pressure. Anything lower will provide the same pressure at same PSI in same size cylinder. If you run it a a lower than rated pressure it should last longer.
 
Yeah its fine, its kinda like asking if its ok to drive at lamborghini at 35 mph.
Del

The pressure will affect the tonnage rating. I run mine at 3000 and its about 30 tons, if I ran it at 2500 it would lower the tonnage rating.
 
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