HP fills

[jaycanwk]

Quick question, out of curiousity. I've noticed quite a few people saying that "most shops can't do fills above 3000psi" or have a hard time with it, when discussing the benifits of HP vs LP.

My question is, where are all these shops that can't do HP fills? Any shop I've been to here in Onatrio have been able to fill my HP tanks just fine, as well as a few shops I went to in Florida, and I didn't think to ask ahead of time, I just droped off my tanks, and they were nicely filled to between 3400 -3500 when I picked them up. I would think that "most shops have toubles filling HP tanks" really isn't true anymore today, especially in areas where diving is popular. But then again I don't get out as much as some of you.

 

[HeyJT]

My persoanl experience is most shops do "quick fills" on my HP (3442 psi) tank . By the time I pick it up, the pressure is at or below 3000--sometimes 2,700 psi. The shops that do HP fills and do fills in water, typically fill to to at least 3400 to 3500. I've found the smaller LDSs do a better job at fills than the big guys.

 

[LobstaMan]

Most shops that I have had experience with can do the HP fills. But, I have a habit of leaving my tanks overnght to ensure proper fills. When I pick them up they're nice and cool and then can be checked and topped off if needed. A hot or quick fill defeats one of the purposes of the HP tanks, namely more gas in a smaller package.

LobstaMan

 

[HeyJT]

Most shops that I have had experience with can do the HP fills. But, I have a habit of leaving my tanks overnght to ensure proper fills. When I pick them up they're nice and cool and then can be checked and topped off if needed. A hot or quick fill defeats one of the purposes of the HP tanks, namely more gas in a smaller package.

LobstaMan

Very true. Sometimes I need quick fills between dives. The shops with water tank filling stations do a better job. I also ask for a 10% overfill, which puts me at the proper working pressure by the time i hit the water

 

[argos59]

a aaa

 

[robzr]

My persoanl experience is most shops do "quick fills" on my HP (3442 psi) tank . By the time I pick it up, the pressure is at or below 3000--sometimes 2,700 psi. The shops that do HP fills and do fills in water, typically fill to to at least 3400 to 3500. I've found the smaller LDSs do a better job at fills than the big guys.

If they filled it initially to 3442 psi and it cooled to 2700 psi, assuming it was 2700 psi @ 72 farenheit, it would have to be heated up to 218 f @ 3442... probably a short fill!

Rob

 

[theskull]

In addition to the unintentional short fills due to "hot" fills, you can run in to:

Compressors that are not rated past 3000
Small or no storage banks and too many tanks needing fills for the time allotted
Poorly trained tank monkeys who think 3000 is a fill

Still, if you get your HP tanks properly filled the majority of the time you are still way ahead if you just have to live with a short fill on occasion. Especially with the larger capacity tanks, where an underfill still gives you 80 cf or more.

theskull

 

[spectrum]

Quick question, out of curiousity. I've noticed quite a few people saying that "most shops can't do fills above 3000psi" or have a hard time with it, when discussing the benifits of HP vs LP.

My question is, where are all these shops that can't do HP fills? Any shop I've been to here in Onatrio have been able to fill my HP tanks just fine, as well as a few shops I went to in Florida, and I didn't think to ask ahead of time, I just droped off my tanks, and they were nicely filled to between 3400 -3500 when I picked them up. I would think that "most shops have toubles filling HP tanks" really isn't true anymore today, especially in areas where diving is popular. But then again I don't get out as much as some of you.

I agree, most have the capacity but many don't have the inclination (or gray matter) to do a good job. The physics of it all just makes it a little harder. A good shop that you can count on to do a top-off after cooling down is very helpful. If a shop will do a wet fill with a slight overfill you can go home in good shape. Things like cold air in the banks or walking in with cold cylinders also help. Under the worst conditions a nice slow fill to the service limit won't drop much more than 200 PSI. This is my experience with PST E7-80s.

As much as we harp on this as a HP steel issue I have plenty of AL80 dive buddies routinely show up with 2700 to 2800 PSI in summertime weather. The neutral aluminum 80 crowd isn't much better off with a 3300 service pressure and all that aluminum mass.

The red flag goes up if you will be diving from a boat or region that does not have HP and they do exist.

Pete

 

[Cold_H2O]

I always ask to have my tanks "topped off" before I take them home.
It is best if you can leave your HP tanks for several hours or overnight to get the best fill.

I prefer my tanks be filled slowly and not in a water bath.

I have no trouble getting a nice fill of 3500 PSI once I have made it clear that for me and my HP tanks that is the required fill.

 

[Cheekymonkey]

Many times its not about them not being ABLE to do a HP fill, its htat they don't WANT to due to the supposed ( I'm not sure whether its true one way or another ) stress it places on the compressor.