Adaptors and fittings for full pressure flipper

[woody]

Re: Adaptors and fittings for full pressure flipper

Since liquid CO2 is a lot more dense than the gaseous form, the small flow from the paintball on/off valve is not a issue any more, right? Is it worth to use a dip tube?

I estimated that liquid gave a 10 fold improvement....I'd use a tube that dipped IN the liquid IF deciding to go with a liquid feed.

[evristow]

Re: Adaptors and fittings for full pressure flipper

Since CO2 as a gas at 1atm (14.6959 PSI) and 20°C have a density of 1.860g/L, at 56atm (823 PSI) the density would be 104.198g/L. Liquid CO2, at the same 56atm and 20°C have a density of 773g/L, so the expansion ratio is 7.41:1, at 0°C the ratio goes up to 8.29:1 and at -30°C, to 10.82:1! Bullseye Woody!!!

I noticed that the paintball valve have a approximately 1.2mm (0.047) orifice and two 90° internal bends, therefore it's CV is near to 0.056 gal/min @ 60F, to put in SI units, 0.00355 L/s @ 15.5°C, at lower temperatures, since turbulence tends to lower, the flow might increase slightly.

According to Catalina's Paintball tank info, an 16Oz tank have an internal volume of 0.669L, considering that there will be a pressure line and a manifold between the tank and the buffer, it is safe to assume that the total volume is going to be near 0.75L.

Hence, putting all together, at 0°C the liquid from the tank would take little more than 17s to fill a completely empty system to 56atm (823PSI). The volume of the ram is 0.223L, consequently the time to refill the CO2 used on the previous actuation would be 5.15s, a bit too slow for the purpose.

This number should be <3s, which tells me that using liquid, the system I have in mind needs a main valve with at least 0.00688 L/s, equal to a CV of 0.109 gal/min @ 60F, indicating a minimum orifice diameter of 1.8mm (near 0.07)... With this in mind the Paintball valve is out by now, at least until I can manage to disassemble one and check de possibility to enlarge the bore to 2mm, size which would give a CV of 0.161 and a refill time of 2.02s. The Aquamedic and similar valves became even more interesting! Tomorrow I will make some calls.

As the system is going to be liquid fed, I need to buy a propane torch and some cooper tubing to convert the anti-siphon tube, since nowhere sells a siphon or dip tube small enough to fit a 16oz bottle.

For now is back to the drawing board... err CAD

Cheers,
Eduardo

[woody]

Re: Adaptors and fittings for full pressure flipper

I noticed that the paintball valve have a approximately 1.2mm (0.047) orifice and two 90° internal bends, therefore it's CV is near to 0.056 gal/min @ 60F, to put in SI units, 0.00355 L/s @ 15.5°C, at lower temperatures, since turbulence tends to lower, the flow might increase slightly

Um ...yes and no.

The internet gives the definition of Cv as ...

Cv - expresses the flow capacity in gallons per minute (GPM) of 60oF water with a pressure drop of 1 psi (lb/in2).

This is right ...but misleading.

Cv - follows the square root of the pressure drop in psi .... and the above quote is correct because the square root of one is ..yup one!

Q ( flow ) = Cv sqrt(dp/G)

Lower temp will reduce the bottle pressure and the pressure drop ...so the flow will decrease.



http://www.nadi.it/english/utilities_en.html

[woody]

Re: Adaptors and fittings for full pressure flipper

A quick calc using a CV value of 0.056 gives me an initial flow rate of 8.64 litres per sec @ 1 bar ...reducing steadily as the pressure differential decreases.. giving a refill time of 2.7 secs with a gas feed.


http://www.proautocon.com/tools.asp

download the paculator ...ignore the cubic meters value it's...as I recall .. wrongly converted by a factor of 10.

co2 gas density = 1.52

[woody]

Re: Adaptors and fittings for full pressure flipper

I've reread you post...

Since CO2 as a gas at 1atm (14.6959 PSI) and 20°C have a density of 1.860g/L, at 56atm (823 PSI) the density would be 104.198g/L. Liquid CO2, at the same 56atm and 20°C have a density of 773g/L, so the expansion ratio is 7.41:1, at 0°C the ratio goes up to 8.29:1 and at -30°C, to 10.82:1! Bullseye Woody!!!

I noticed that the paintball valve have a approximately 1.2mm (0.047) orifice and two 90° internal bends, therefore it's CV is near to 0.056 gal/min @ 60F, to put in SI units, 0.00355 L/s @ 15.5°C, at lower temperatures, since turbulence tends to lower, the flow might increase slightly.

According to Catalina's Paintball tank info, an 16Oz tank have an internal volume of 0.669L, considering that there will be a pressure line and a manifold between the tank and the buffer, it is safe to assume that the total volume is going to be near 0.75L.

Hence, putting all together, at 0°C the liquid from the tank would take little more than 17s to fill a completely empty system to 56atm (823PSI). The volume of the ram is 0.223L, consequently the time to refill the CO2 used on the previous actuation would be 5.15s, a bit too slow for the purpose.

You appear to have forgotten in the above calcs ( I'm not atm checking for flow formulae errors ) to expand your liquid into gas....divide time by 10.

http://www.valvias.com/flow-equations-f ... -cv-kv.php

Try inputting the following values into the calculator Q = 0.06 l/s delta p= 300 psi S.G. =1.1
Cv output set in us gals and psi

[woody]

Re: Adaptors and fittings for full pressure flipper

I knocked up a spreadsheet using your buffer / ram volumes and a gas feed with a cv of 0.056 then calc the pressure recovery time for two scenario's.

The refilling to full pressure of the buffer and ram = 2.8 secs
The refilling to full pressure of just the buffer tank = 2.1 secs

here's an easier to use calc .. http://www.swagelok.com/tools/CV_Calculator.aspx

co2 gas = 1.53
co2 liquid = 1.1
P1= 870 PSIA
P2= 670 PSIA
Cheers Alan

[woody]

Re: Adaptors and fittings for full pressure flipper

Here's the excel spreadsheet with slightly modified parameters...hopefully it's correct ...it may however be worth what you paid for it!

[attachment=0:15kq0jsg]fill time.xls[/attachment:15kq0jsg]