Sign in to follow this  
territorialmillworks

Hyd tank size

Recommended Posts

Slowy working on a press and wondered how to size the hydraulic tank to the GPM of the pump.  Any suggestions/ideas/thoughts appreciated............

In general the gallonage of a tank equals the output of the pump per minute. 3 gallon/minute pump = 3 gallon tank.

 

This is not a hard and fast rule and seems to be ignored altogether by builders using 2 stage pumps. Too little tank volume and the oil overheats. 

Share this post


Link to post
Share on other sites

In general the gallonage of a tank equals the output of the pump per minute. 3 gallon/minute pump = 3 gallon tank.

 

This is not a hard and fast rule and seems to be ignored altogether by builders using 2 stage pumps. Too little tank volume and the oil overheats. 

 

I agree

Scott

Share this post


Link to post
Share on other sites

Actually the rule of thumb is three to five times without any sort of secondary cooling. Proper consideration should also be given to internal baffling in the tank to make sure the return oil isn't immediately directed back to the pump and to minimize aeration. Duty cycle will change your requirements as well.

Share this post


Link to post
Share on other sites

Actually the rule of thumb is three to five times without any sort of secondary cooling. Proper consideration should also be given to internal baffling in the tank to make sure the return oil isn't immediately directed back to the pump and to minimize aeration. Duty cycle will change your requirements as well.

More is of course better but the text book answer is 1 gallon/gallon of pump volume per minute.

 

Care to source your info?

Share this post


Link to post
Share on other sites
http://hydraulicspneumatics.com/200/TechZone/ReservoirsAcces/Article/False/6448/TechZone-ReservoirsAcces Rules seem to be 3x unless..........and its the unless that seems to fit our usage unless you have three shifts and never turn the unit off where you may want more oil or work in a desert and have a radiator or work in the winter and need to pre-heat the oil or or only limited use or or or It seems its like everything else..if you know the tools and work a plan then you can do things where others will not. Ric

Share this post


Link to post
Share on other sites

Both rules of thumb are correct it depends on usage. For a low volume use like a home shop hyd press 1:1 is plenty. However, for the hydraulic system on our CME 75 drill rig the 110gl. hyd tank would get hot enough to boil snow thrown on it to cool the oil. It ran a 30gpm. pump @ 1,500psi constant and 2,200psi spike load but the auto hammer or cat's head were very hard working devices.

 

At high volume restrictions in the circuits will heat the oil, often more than the motors, cylinders, etc. being driven. If you can hear the oil move there's a restriction, if it's squealing it's really heating the oil. Control valves, especially graduated flow valves hiss even squeal in use but only a couple restrictions in the circuit isn't an issue.

 

Cooling is a lot more important for high volume systems than for high pressure systems. If you use steel pipe for the return lines except where it needs to flex, will go a long way towards cooling the oil. Don't sweat it unless the oil tank gets too hot to hold, think  fresh cup of coffee hot. The easy, REALLY easy way to prevent hot oil channeling directly to the suck hose is a second tank and several return lines between the hot tank and the feed tank. You can't have too large a tank WITHIN REASON! Just don't get silly and larger IS better.

 

Frosty The Lucky.

Share this post


Link to post
Share on other sites

I lucked out. I bought a 6.5gpm pump with a 25 gallon tank already filled attached to it.. $150. I sold the 3ph 5hp motor that came with it and purchased a single phase 6hp to replace it. Scrapping companies can be wonderful. I like the larger size tank, even if I upgrade the pump some day I don't think I'll have to get a larger tank :)

J

Share this post


Link to post
Share on other sites

Looks like there is still room in this old brain bucket. 

Thanks for the update fellas. 

 

OP: great score. Too much is always enough. 

Share this post


Link to post
Share on other sites

In regards to my source, its NFPA (National Fluid Power Association )/ T3.16.2 or ANSI B93.18 if you want the specific language, plus almost 25 years working as an engineer in mobile hydraulic systems. I also added the caveat about duty cycle which in most of our home shops is limited as other posts since mine have also pointed out so your mileage will vary considerably depending on usage.

Even a quick Google search with "sizing hydraulic reservoirs" comes up with 2-3x pump flow, not that I put much faith in that without investigating sources

Share this post


Link to post
Share on other sites

Unless you blow a hose, a little Hydraulic fluid goes a long way!

 

You might install a quick shut off.

​Unless you have a good pressure bypass at the pump the only safe place for a quick shut off is the motor driving it! Yeah, I know hyd pumps have built in pressure bypass valves but anything can fail and having a run away pressure spike blow something is a . . .B-A-D thing.

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Was the fluid hot? I caught a blast from a blown fitting almost smack in the face. Fortunately it was winter and I was wearing my Refridgeware (Insulated coveralls) and and just enough warning to duck and take it on the hood. While I didn't get burned it nearly baked me like a potato while I made my way back to the truck and changed out.

Now the point I was wondering about, I assume your hair was soaked like mine. Was it really soft til it grew out like  mine was?

Unlike you nobody laughing at me was on my marrying radar. Some guys have all the luck.

Frosty The Lucky.

Share this post


Link to post
Share on other sites

I've been sprayed a couple of times, luckily not at high pressure. My tradesman got me good one day. We were laying under a banana bagging machine removing the slue rams and unknown to me at the time to get them out the rams needed to be retracted and their oil emptied. I loosened the fitting and removed the hose letting the oil drop into a drip tray directly under the cylinder but no, my tradesman gave the rod a good hard push spraying me with the entire contents of the cylinder hahaha. Was a good laugh at the time but man being covered in hydraulic oil for the rest of the day in 38 degree c heat 90% humidity is not fun. The oil stops you from sweating and no matter how much you try to wipe it off with rags and such it's still there.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this