New Compressor Owner...

[p1p]

Just purchased a Franken Compressor built from a Bauer Capitano Head.

Now the builder suggested I change oil and filter anywhere from 15 hours to 25 hours. I have yet to figure out how to change oil on it yet, figure it cant be too difficult.

I do have a question on bank bottles if I may.

As an infrequent user (maybe 2 tanks a weekend), do I really need bank bottles? Compressor time is same filling a bank, or a tank, its just the convienence of not firing up the compressor for a quick fill.

Now what I dont quite follow is "cascading" bottles.

So if I have 2 3600psi bank bottles cascaded, what is my working pressure at the end of the line? Also, if someone could explain cascading, I'd appreciate it. In the meanswhile I'll search some more.

My compressor came fully setup to pump nitrox (o2 bottle, mixing stick, analyzer, etc). Just awaiting the needle valve for fine tuning O2.

 

[VooDooGasMan]

Jeff searching this forum has many threads,the second is The technical guide to Gas Blending by nicos raftis.

The third is Ron Ault the owner of Hoodsport and dive has a vast experience and will talk to you about it, I think scott boyd has info on his website also.

ENJOY.

 

[kwindham]

each time you open a valve to fill the new tank, you would use the following equation to find the final pressure (Pf) in the tank to be filled:

((P1)(V1) + (P2)(V2))/(V1 + V2) = Pf

Where
P1 = Pressure in cascade bottle
P2 = Initial pressure in your scuba bottle
Pf = Final pressure of both bottles after you open the valve

V1 = Volume of cascade bottle
V2 = Volume of your scuba bottle

Its essentially a weighted average based on volume. Notice that if both bottles have the same volume, the v's cancel and the equation simplifies to a simple average: (P1 + P2)/2 = Pf

So just to use a simple example to make calculations easy, let's say you have three cascade bottles filled to 3600 psi, your scuba bottle is the same volume as the cascade bottle (and starts at 0 psi), and you perform three fills. Here are the calculations:

(3600 + 0)/2 = 1800 (fill #1: pressure in both bottles has equalized to 1800 psi)
(3600+1800)/2 = 2700 (fill #2: because your scuba bottle already had 1800 psi, it raised slightly to 2700psi)
(3600 +2700)/2 = 3150 (fill #3: pretty close to 3600 without a gas booster :blinking

Anyway, you get the idea. The process is similar with bottles of different volume...

 

[p1p]

ah thx. Seems perhaps a booster is in my near future.

And thx for the reccommend on Scott Boyd VoodooGasMan, David at Federal Way UWS said the same.

 

[Peter_C]

For two tanks a weekend banks don't make much sense, since they can cost quite a bit upfront if you can even find them used. You still have to run the compressor, just less often, but for a longer time. I ran my compressor for 3.6 hours today filling the banks, and topping up a few tanks at the same time. Fortunately I have auto drains and don't have to pay much attention to it. If you use high pressure tanks some of the banks would need to be 4,500 psi to be of much good for cascading. Otherwise a booster would be needed and they are expensive.

A larger filter might be a good thing, if you don't already have one instead of bank bottles. If you plan on pumping nitrox, I would recommend putting a solenoid on the O2 to shut it off when the compressor shuts off. Of course a CO meter wouldn't hurt either.

 

[p1p]

I've got a 31in filter on mine (for a MAKO PD-1803)

Its been suggested I perhaps look into additional water filtering?

I would think that size filter should result in pretty dry air.