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SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Dry ice pneumatic tool

Higher ATM is to make up for the lower cfm volume storage and the regulator keeps the tool protected not the direct storage pressure.

https://www.finepowertools.com/air/comp … ct-wrench/

CFM Chart: Impact Wrench Air Consumption

Tool Size    Air Consumption    Pressure
1/4-inch Impact Wrench    2 CFM    90 PSI
3/8-inch Impact Wrench    3 CFM    90 PSI
1/2-Inch Impact Wrench    5 CFM    90-100 PSI
3/4-inch Impact Wrench    7 CFM    90-100

https://tooltally.com/what-size-air-com … do-i-need/

TOOL    REQUIRED PSI    REQUIRED CFM @ 90 …    SUGGESTED COMPRESSOR SIZE:
Sand Blaster (#4 Nozzle)    60-125    70    Rotary Compressor
Disc Sander    90-100    20    80-Gallon
Dual Action Sander    90    15    80-Gallon
1" Impact Driver    90-100    12    60-Gallon

https://www.redhillsupply.com/air-compr … -info.htm/

AIR TOOL PRESSURE R…    PORTABLE TOOLS    AIR COMPRESSOR CFM …    AIR TOOL PRESSURE R…
70-100    Air Filter Cleaner**    3.0    HAMMERS
70-100    Body Polisher**    20.0    90-100
70-100    Body Sander (Orbital)**    10.0    90-100
70-100    Brake Tester    4.0    125-150

https://www.vmacair.com/blog/what-size- … air-tools/

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,383

Re: Dry ice pneumatic tool

For SpaceNut re Pneumatic Tool ...

I think your point about having pressure greater in the boiler than is needed by the tool makes sense, but I'm pretty sure we don't need to exceed 8 ATM.

The possible exception might be the tool that is used for Brake testing, which needs 10 ATM.

The greater the pressure to be held by the tank the greater the mass of the walls.

For that reason, I recommend trying to avoid going as high as 20 ATM ...

1900 psi is the capability of the precision chamber shown in a post earlier in this topic ...

1900/15 >> 380/3 >> 126 ATM ... we don't need to go anywhere ** near ** that high for this application.

If you visit a show room with Pneumatic tool equipment, you'll get a sense of the scale of equipment in daily use in the United States and probably elsewhere.

The difference with ** this ** application is the need to admit heat into the interior of the boiler, and for that the example of steam boilers would appear to point the way forward.

The challenge for all designs is how to deal with the initial state of the feed stock, which is solid at 1 ATM, or in the case of Mars, a fraction of an ATM.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Dry ice pneumatic tool

A one chamber does all cause long ramp up cool down cycles and the size of the chamber volume is the limited for the cfm in the can as the solid takes up all of the size.

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,383

Re: Dry ice pneumatic tool

Here is a reply from Parr Instruments ... the content looks applicable to far more than just this immediate topic, so I'm adding search terms ...

SearchTerm:Parr Instruments reply regarding design of pressure vessel for Mars (or Earth)
SearchTerm:Pressure vessel design

To all ... please suggest additional search terms that would help you find this post in future ...

20210412

-Tom

Good afternoon!  Sure thing; you can see how these vessels are opened and closed from the below:

https://www.parrinst.com/support/videos/

There are a number of videos there; the relevant one for understanding the opening and closing is on the left hand column, second one down under “Reactors and Pressure Vessels”.  Envision one of these with a boltless split ring closure; an o-ring seal would eliminate the need for tightening bolts.  The o-ring must be specified for use with CO2, but this is doable; as you’re probably aware, CO2 destroys o-rings of many flavors but it is a manageable problem.  However, kbd512’s concern about abrasive dust may yet slay the o-ring design altogether.  A compressed flat gasket will be more resistant to this real-world complication.  Or use an already sealed vessel with a simple ball valve on top for solid CO2 loading; the ball valve seat tends to wipe solids away as the valve is closed.

This may well knock Parr out of the running, but I’m not certain that our vessels are competitive at this pressure range of 100-200 psi.  A 1-gal vessel from us will cost perhaps $10K USD, as opposed to a welded fabricated vessel for closer to $1K.  When you get to pressure vessel manufacturers, there are roughly two types: sheet metal fabricators and milled pressure vessel manufacturers like Parr.  The sheet metal fabricators take sheet metal, roll it and weld it, and 200 psi is the typical pressure limit.  Milled pressure vessel manufacturers like Parr take solid metal bar and machine the inside out of it and we think 1900 psi is the right pressure limit.

The sheet metal approach can deliver a vessel for under $1K, and at this price point it makes sense to make them by the dozens and put them on the shelf until someone needs it.  So if you go that approach you can likely get it immediately, but you’re unlikely to get it customized and it’s tough to get someone who can customize the design very far.  The milled metal approach supports businesses who make things on demand, which really just means you’ll have to wait 6-8 weeks for it to be constructed, but it can be highly customized and would include a design phase where you can do things such as evaluate the seal feasibility and compatibility with the robotics available to you.  And when you’re done it will weigh a lot; about 80-lbs for a 1-gal, though we can thin the walls down to maybe 50-lbs with some effort.

So for proof of concept you might want to try a less expensive sheet metal vessel.  It’s immediate and cost effective.  But don’t expect to customize it to vet feasibility of use.  For that you’re likely into a milled vessel which will take 4-6 weeks, cost much more, and weigh a lot more.

I hope this helps.  Please let me know your thoughts!

Best regards,

Conan

From: tahanson43206
Sent: Saturday, April 3, 2021 1:19 PM
To: Collins, Conan <conan.collins@parrinst.com>;
Subject: 20210403 Fwd: Fw: United States - Custom Systems Google search for clamshell pressure vessel

Dear Mr. Collins,

Thank you for your helpful and encouraging reply to my inquiry!

Please note that I posted a link to an image from your web site to advance discussion.

http://newmars.com/forums/viewtopic.php … 99#p178199

By any chance, do you have (or can you point to) YouTube video (or equivalent) showing how an operator works with the example pressure vessel?

As noted in my post, the pressure we are contemplating is on the order of 100 psi with a high of 200 psi, so 1900 psi is a bit stronger than needed.

Please note that in addition to the Mars application, I am definitely interested in the Earth-side potential of a Dry Ice Pneumatic tool supply system.

A cubic foot (7 gallons) is the size of chamber I am thinking about for an Earth-side demonstration.
<snip>

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: Dry ice pneumatic tool

repost

I'd forgotten about this. It does seem that my original thought, that you could capture CO and oxygen from the atmosphere   and have a ready made energy store when humans landed a couple of years later is not so crazy and could work. Whether it's worth going to that trouble compared with just loading 30 tons of methane and oxygen on a Starship is another matter. I guess boil off over two months might be an issue?

If I read this correctly, Louis is suggesting the capture of CO and O2 already in the atmosphere on Mars.

It could be done, but it is no trivial undertaking.  The Martian atmosphere is 95% CO2, 2% Argon, 2.8% Nitrogen, 0.174% O2 and 0.0747% CO.  For this to work, you must first separate the CO2 from the other gases.  The CO2 in the Martian atmosphere is close to its triple point temperature, so relatively little compressor work would be needed to increase its density relative to the other components.  The remaining gases would be 40% Argon, 56% N2, 3.48% O2 and 1.49% CO, by volume.  The CO would be about 1% by mass.  On this basis, the calorific value of the non-CO2 content of the Martian atmosphere is about 100KJ/kg ( CO heat of combustion is 10MJ/kg).  At 1bar, the mixture would have volumetric energy density of 150KJ/m3.  At 300bar, it would be 45MJ/m3.  Because the CO and O2 are present in low concentration, you could probably store the mixture in a single tank, without risk of explosion.  To burn it, you would may need to pass it through a heated catalyst bed, as the concentration of fuel and oxidiser is too low to support flaming combustion, even under extreme compression.

In terms of total work output, one needs to compress 19kg of CO2 for every 1kg of stored gas mixture, which would release 100KJ of energy when released.  Put another way, the chemical energy content of the Martian atmosphere is 5KJ/kg or 65J per cubic metre at 6.1mbar.  This is almost certainly too little for any release of net energy from compressing and combustion of the Martian atmosphere.  None the less, it may be interesting to consider this as an energy storage mechanism.  The compressed CO2 has its own value as a CAES working fluid.  Heating it above 31°C would produce high pressure gas that could drive a compact gas turbine.  The stored compressed residual CO containing mixture has chemical energy density 100KJ/kg.  Taking the Cv of the gas to be 1KJ/Kg.K, complete combustion would raise the temperature of the gas by 100°C.  So along with its internal pressure energy, it could be a useful energy storage mechanism for short range vehicles and compressed air tools.  It is worthy of further investigation, I think.