mike_s:
My LSD charges $20 or $25 per tank.
We actually have a local Hydro facility, which I can take them to I think for $12 or $15, which is where the dive shop takes them. What you get extra out taking them to the dive shop is that our shop cleans them after they've been to the hydro place. The water they put in the tanks for the hydro isn't clean and you get residue in the water from other tanks they did, so you could get dirt, oil, a "film", etc on the inside of your tank... Remember the hdyro place also used the same hydro machines to do fire extingisher tanks, welding tanks, propane tanks, etc. Lots of crap to contaminate your tank...I have seen other shops charge $50 for a hydro, but that included the hydro, visusal, and a tank of air.
I'd find a different hydro test facility or I'd reconsider the honesty of your local dive shop. Their price ($5.00 to $10.00 over cost)is still quite reasonable for the pickup and delivery service provided, but if they are telling you they have to clean the tanks after testing, they are putting one over on you. Personally, alarm bells go off anytime anyone lies to me as it always makes me wonder what else they are willing to fib to me about.
Tanks are filled with water for the hydro test, an o-ring sealed test fitting is installed in the tank and the tank is then placed in a water jacket for the test. The tank is pumped up to test pressure with more clean water. After it is removed from the water tank the rest fitting is removed and the tank is drained, dried and visually inspected.
I have never heard of a shop reusing the the water from one tank by placing it in another. It's also important to remember that the stock in trade of hydro test companies is normally CO2 cylinders for soda distributors, and O2 cylinders for Medical O2 suppliers and welding gas suppliers. So probably 1/2 to 2/3rds of the tanks tested are destined for 100% O2 service by end users who will do no further inspection or cleaning of the tanks. So trust me, if a hydro test facility is getting oil or other contaminants in tanks, they will not stay in business long. Unless you have read in the local paper about welding and medical O2 tanks blowing up all over the place recently, it's a safe bet the tanks leave the hydro test facility at least as clean as they entered.
A VIP is also a mandatory part of the hydro test as is done as part of the hydro test. Consequently what a dive shop effectively does after a hydro only consists of slapping their own VIP sticker on the side of the tank. If they actually de-valve the tank again and re-inspect it, it is redundant and just a waste of time, or at best gives them the piece of mind of VIP'ing it for themselves. It does not benefit you and you already paid for one VIP with the hydro plus you paid the shop's markup so any charge over about $ 0.50 for the cost of the sticker is a rip off.
If part of the cost is paying the dive shop to clean the tank after hydro, I'd insist on watching them do it. If they are concerned about oil contamination during the hydro test (very unlikely for the reasons stated above) then the procedures used are either going to be fairly extensive and probably adequate to clear the tank for O2 service or it is just going to be a water rinse and dry that will be inadequate and would serve only to create the opportunity for more flash rust if you own a steel tank.
Locally the LDS is co-located and co-owned by the hydro test facility. A hydro is done on site in 24-48 hours for $15.00 and includes the hydro test, the VIP and shop VIP sticker and an air fill. A nitrox fill costs $5.00 more.
