Increasing Tank PSI

[Thunder Bay Minnow]

Could someone please educate me.

I have been told that it is possible to get a tank "plus" rated.

Meaning if a steel tank is rated at 2400 that it is possible to get it rated for a higher PSI.

I spoke to the local fire extingusher store that seems to do all of the hydros in the area and he said that it is possible to get it rated for 2400 and an additional 10% for a total of 2640.

When I get them filled, I am already getting the 2640 allowed by steel.

Is it true that a tank can be plus rated so that a 2400 can DOT legally be filled more than 2640?

And if so, how?

Thanks !

Jeff

 

[Rick Murchison]

Could someone please educate me.

I have been told that it is possible to get a tank "plus" rated.

Meaning if a steel tank is rated at 2400 that it is possible to get it rated for a higher PSI.

I spoke to the local fire extingusher store that seems to do all of the hydros in the area and he said that it is possible to get it rated for 2400 and an additional 10% for a total of 2640.

When I get them filled, I am already getting the 2640 allowed by steel.

Is it true that a tank can be plus rated so that a 2400 can DOT legally be filled more than 2640?

And if so, how?

Thanks !

Jeff

The "+" rating allows the 10% overfill on steel tanks.
Many folks are under the impression that the "+" rating "expires" at the first hydro - this isn't so, and a hydro facility that knows what they're doing can continue to issue - and stamp - the "+" as part of their hydro. (you do have to ask for it )
DOT doesn't allow more than the 10% overfill.
As a practical matter, many folks grossly overfill steel tanks routinely.
I don't recommend it.
Rick

 

[firemedic1015]

The plus rating was a system that was implemented during WW II when there was a shortage of cylinders to ship gasses to the war zone in. The theory behind it was that if we increase the pressure we'll increase the contents and need less cylinders. Practical application in today's world is this: New low pressure steel cylinders built to the 3AA standard are shipped from the factory with a plus rating beside the hydro and thus allow the 10% overfill. Manufacturers take this into account when they rate the cylinder, for example, a lp85 is rated for 85 cu/ft of gas at 2640psi. If that cylinder did not have the plus rating on the current hydro stamp it would only be able to be filled to 2400 psi with a capacity of 77 cu/ft. One common misconception regarding the plus rating is that it can only be applied to the first hydro of a new tank. This is not correct. Any time that a hydro facility tests a tank they can test it to the plus standard. This is done using the REE number for that given cylinder, most new cylinders have this stamped on the tank neck. Older cylinders often do not, and the hydro facility is not willing to seek the number out so they just don't do the plus test. This is often the case with older steel 72's. Shops should not be filling tanks without the plus rating to 2640 because these tanks are not rated for that pressure. With all of that said, there are a great number of divers, particularly in cave country that fill low pressure tanks to 4000psi on a regular basis without any detrimental effect. A search on this topic should yield a great deal of information.

Zeb

 

[Rick Inman]

As a practical matter, many folks grossly overfill steel tanks routinely.
I don't recommend it.
Rick

Gee, and you being so close to cave country.

Didn't I read on the internet that they do a zillion test cycles at a million psi? And that the same tanks are rated much higher in Europe (must have to do with translating to the euro, or something).

Seriously, I think that the incidence of overfilled steel tanks failing is almost non-existent.

But, I also (publicly) do not recommend it. However (privately) I routinely fill my 95's (rated to 2640) to 3000psi. That way I have more gas than my buddy with his hp100's who can't seem to get a full fill.

 

[fweber]

The afoementioned information is correct. The most common determinant as to getting a tank plus rated, is whether it has the REE (Reject Elestic Expansion) stamped on it or not. With the REE the hydro tester only has to do some very simple arithmetic. Without the REE a tank can still be plus rated, but, the arithmetic is somewhat more involved and most shops aren't willing to take the extra steps involved.

 

[spectrum]

The afoementioned information is correct. The most common determinant as to getting a tank plus rated, is whether it has the REE (Reject Elestic Expansion) stamped on it or not. With the REE the hydro tester only has to do some very simple arithmetic. Without the REE a tank can still be plus rated, but, the arithmetic is somewhat more involved and most shops aren't willing to take the extra steps involved.

That is true but it's important to make sure the tester knows that the customer actively seeks to renew or even restore the +. The odds of them doing that extra step will be better. Some routinely do not bother unless asked.

Pete

 

[fweber]

That is true but it's important to make sure the tester knows that the customer actively seeks to renew or even restore the +. The odds of them doing that extra step will be better. Some routinely do not bother unless asked.

Pete

True enough.......if you don't ask for it........you won't get it.

 

[Scared Silly]

Didn't I read on the internet that they do a zillion test cycles at a million psi? And that the same tanks are rated much higher in Europe (must have to do with translating to the euro, or something).

Na it is not the Euro, it has to with the temperature. It is that 1.8 factor ya gotta use to get the right fill pressure. :14:


For clairity the above post and Ricks are is spoof. Many people think because a cyliider in the US and a cylinder in the EU that are made by the same manufacturer and have the same physical size they are the same cylinder. They are not - different metals are used which changes their ultimate strength and accordingly their fill pressures.

 

[Thunder Bay Minnow]

Jeff,

I guess you didn't get this message. Sorry for the bad news.
-----Original Message-----
From: Rumachik, Steve
Sent: Thursday, July 26, 2007 2:00 PM
To: 'jeffthorton@hotmail.com'
Subject: FW: Additional Tank - NOT duplicate


Jeff,

Sorry to report that we do not have on file the REE for this cylinder. We have not made this cylinder since the mid 1980's. Recently we became a different company and moved to a new location. We left behind records older than 15 years.

Steve Rumachik
PST
-----Original Message-----
From: Rumachik, Steve
Sent: Monday, July 23, 2007 1:59 PM
To: 'Jeff Thornton'
Subject: RE: Additional Tank - NOT duplicate


Jeff,

The most these cylinders can legally be pressurized is 2640 psi (2400 + 10%).

Regards,

Steve Rumachik
Product Manager
PST CYLINDERS
414 431 0275

-----Original Message-----
From: Jeff Thornton [mailto:jeffthornton@hotmail.com]
Sent: Monday, July 23, 2007 12:57 PM
To: sales
Subject: Additional Tank - NOT duplicate



This is not a duplicate email. I have addtional information on a second tank.
I understand that it is possible to get an existing tank certified for more PSI than what is stamped on the cylinder. I know that it is currently 2400+10%. But I am told that it could be possible to increase the PSI if I had the appropriate documentation.
One of my tanks is due to get Hydro this week. Here is the data on both of my cylinders. Is this possible?
****First Tank*****
DOT 3AA2400
5845-2Y PST
****Second Tank****
DOT3AA2400
30597
SRP
8C72 PST
Thank you for any assistance that you can provide.
Jeff Thornton

​

 

[CompuDude]

Here's a related question:

Faber LP95, last hydro'd in 2003. No plus stamp, but who knows if the prior owner took it to a place (and requested) that could do the proper tests for that.

Is it worth having it re-hydro'd early to get that plus rating?