Using a CNG Refill Adaptor

[Dancrosswis]

Hi Folks,

We had a good Memorial Weekend cruise visiting Door County (WI).  Great food with lots of pots going and, a first, a little oven action.  And then we ran out of CNG.  Water for the last morning's coffee heated slowly on the grill.

Fortunately, Marinette has a CNG pump.  I've made a CNG refill adapter along the lines of our Tech Wiki article, modified to include a needle valve as described at http://forums.sailboatowners.com/index.php?threads/cng-refilling.168890/.  And, I used it once last year, an episode that left me uncomfortable.  So, I thought I'd canvas the experience of others before reconnecting to the hose.

Here is the sequence of events last year (as I recall; I've got contemporaneous notes on the boat), this is at a 3600 PSI pump:

   
• Tank valve is off
• Attached adapter to tank
• Set needle valve to about 1/4 open
• Attached pump hose to adapter
• Paid the pump
• Turned on the pump
• Adapter gauge pegged at 4,000 PSI (it's limit)
• Pump turned off?
• Opened tank valve
• Tank filled slowly until I shut off the tank value at 2200 PSI.  Adjusting needle valve did not appear to affect flow rate.
• No sale registered at the pump

I'm not sure how to interpret what happened.  My theory is the pump quickly turned itself off when the pressure at the end of its hose shot up.  The CNG that filled my tank may simply have been in the hose? 

Next time, I suspect that I should open the tank valve before turning on the pump, so the gas has a larger volume to rush into.  How worried should I be about that 4k+ PSI spike?

I haven't found a step by step description of the refill process.  I'd like feedback on whether my procedure sounds right.  Any suggestions on the needle valve setting?  Any other suggestions are welcomed.

Thanks,
Dan Cross

[Stu Jackson]

Dan,

Post this on www.catalinaowners.com or www.sailboarowners.com and Steve Dion may see it.  He has a refill adapter that he made and has been using it for at least four years.  He'll know.

[Ken Juul]

Then please post the answer here so it will be available for the next person.

[Dancrosswis]

Guys,

Thanks for the suggestions.  I'll post any response I get.

Dan Cross
Ennui Went
1968 #159