Brand new HP100 air fills

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Charging extra for HP fills is BS, I’ve never heard of this happening and would certainly not come back to a shop that was this chintzy.

Pretty common here in the Midwest. Depending on where you live, you may not have much choice in the way of dive shops.
 
With a couple of exceptions, I dive LP72s and HP120s and get them filled at a dive shop. Dealing with short fills is part of the process for me.

I use two shops. Either way, I make every effort to leave cylinders for a whole day because I know that both shops run their cascade at 3600 PSI and in most cases won't be able to get me a good fill without starting the compressor and refilling the cascade, and then topping off my cylinders after they are cooled.

If I am going to be in a hurry, I call ahead and let them know, so they can fill the cascade in advance if they want. This is rare, and when I ask, they know I really need it.

I bring a tank checker and check the pressure of every tank I pick up, and if they are short more than 100 PSI I respectfully ask for them to be topped up. It has always been my experience that the shop is happy to do this; it is hard to get the fills exactly right and we both know it, and I am careful not to be a jerk and not to be in a hurry. Occasionally I find a cylinder that wasn't filled at all especially if I drop off several at once. In the real world, it happens.

I do this for both the LP and HP tanks. Short fills with the LP tanks are less common, but do occur.

There are some area shops that charge extra for HP fills. I don't use those shops because it isn't economical for me to do so. If they were the only shop in the area, well, I'd pay them what they charge in order to enjoy a long, relaxing dive.

I have a large fleet of tanks and typically get 8-10 fills at a time, and around 100 fills over the course of a year. I am paying them a substantial amount for fills and respectfully expect a commensurate level of service.
 
Interersting thread. It appears that low fills on HP cylinders are not all that uncommon in some places, either due to shop policy or failure on the part of the person doing the fill to pay attention to the actual working pressure of the cylinder (which I really don't understand, BTW. ADDENDUM: I grew up in a shop that had a standard, PRINTED AND POSTED ON THE WALL, fill station protocol. Before filling the cylinder, the operator would - among other things - a) check the visual inspection sticker / date, b) check the stamped 'hydro' date, and c) check the also stamped working pressure. I have trouble seeing an excuse for not knowing the 'fill to' pressure, beyond what Jim mentions, below.)

One additional reason may be that the shop doesn't have a compressor that will actually get to 3442/3500 psi. :) I work at one shop that had that issue for a number of years - we had a very 'mature' Worthington compressor that couldn't get past ~3100 psi on its best day. We finally (and, thankfully) HAD to buy a new compressor. But, we would also tell a customer with HP cylinders, in advance, that we could not give them a full fill.

The idea of actually charging more for a full HP fill seems, at first, to be a problem. But, I can understand, if you don't have banks of storage cylinders, and run everything off the compressor, that it is extra work and time. And, as long as the customer knows that up front, they can choose whether to have a less than full fill, or pay extra. That seems fair.

For me, since I dive primarily HP cylinders, I prefer to use a fill station that can give me a full cylinder. But, for quarry dives, it really isn't an issue worth getting upset about.
 
I constantly had issues with short fills in my HP tanks in the Midwest for a combination of reasons most of them being laziness and/or sloppiness on the fill operators part. Now that I've moved to South FL it pretty much never occurs. A "short fill" for me now is a proper 3442 psi fill. The shops I use typically fill my tanks to 3600-4000 psi cooled. It's nice!
 
I have been meaning to ask.

AL80s of even the same manufacturer and close manufacturing date appear to have different surface temperatures when filled from the same manifold at the same time.

I havent used an infrared thermometer, but have noticed a significant difference.

any hypotheses?
Is that also with the same starting pressure in the tanks?
 
The textbook answer for fill rate is no faster the 600 psi per min. But I have found that still leaves a considerable amount of psi lose to temp drop. I try to keep it in the 400 psi range.
 
We charged a little more for higher capacity cylinders. i.e. 80 cf, 100, 120's. Hp didn't get in the equation as there are HP 80's around. We charged Nirox by CF filled irrespective of pressure. Our normal bank pressure was 5K
 
https://www.shearwater.com/products/swift/

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