another burst disk question ?

[idive2]

I have been looking at some burst disks on a few of my tanks.
I have some burst disks labeled 4000-120 3000. And some
others labeled 5000 3000. I've never been clear with the burst disk rating
as it relates to the test pressure rating. Just wondering if the higher
number is always the burst disk rating or is this ever a test pressure
value ? Is the burst disk rating always lower than the test pressure
value ? What is the difference between my bust disks labeled 4000-120 3000
and my burst disk labeled 5000 3000 ?

 

[Hallmac]

The manufactures part number.

 

[DA Aquamaster]

For 3AA and 3AL tanks the test pressure is 5/3rds the service pressure.

For special permit and exempt tanks the test pressure is normally 3/2s the test pressure.

In all cases the DOT specifies the burst disc must fail at between 90% and 100% of the test pressure.

It depends on the manufacturer how the assembly is marked. In most cases however it wil be marked according to service pressure but in some cases may reflect test pressure.

In your case 5000 3000 would reflect a burst disc assembly intended for a 3000 psi tank (like a standard aluminum 80, or the short mid pressure 3000 psi steel 72.

4000-120 3000 sounds like just a part number.

 

[idive2]

In your case 5000 3000 would reflect a burst disc assembly intended for a 3000 psi tank (like a standard aluminum 80, or the short mid pressure 3000 psi steel 72. 4000-120 3000 sounds like just a part number.

Yeah, the 5000 3000 made sense it was the other disk that made less sense, especially the choice of 4000 as part of a part number ?
Since there are other disks with this 4000 as a test pressure one might think that the 4000 in the 4000-120 3000 might be a pressure
value ? Probably not the best choice of part numbers in order to avoid any confusion.

 

[DA Aquamaster]

With the older separate copper discs some companies used 2 digit numbers that did not directly relate to a test pressure or service pressure - you had to look them up in a table or have them memorized. That was pretty stupid too.

1,800 psi tanks use a 3,000 psi test pressure and 2,250 psi tanks use a TP of 3,750 psi and 2,400 psi tanks use a test pressure of 4,000 psi.

So I suppose it could reference a 4000 psi TP, but it could also reference a 3000 psi TP.