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Carbon Monoxide Filters

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viperdoc(at)mindspring.co
Guest

Posted: Sun Aug 26, 2007 7:42 am Post subject: Carbon Monoxide Filters

[img]cid:image001.jpg(at)01C7E7C0.85EF7B70[/img]    

Gentlemen:  

I am in the process of developing a filter for removing carbon monoxide from the cockpit air. I am working under license with the manufacturer of the substrate (they hold the patent). Anyway before I sink any farther funds into this project, I need to do a survey as to interest in this product.   

The system takes ram and ambient cockpit air, passes it through the catalyst that converts the Carbon Monoxide (CO) to Carbon Dioxide. This is farther filtered to end up with Oxygen and Water. This system will require the wear of an aviator’s O2 mask to ensure that no ambient unfiltered air is inspired. The CO substrate is refurbish able but the other filter substrates have to be discarded (replaced) when the indicator turns color meaning the converting ability of the medium has been exhausted.   

The Carbon Monoxide testing I have done so far on the 52 and 50 have shown that there is a significant problem. The average CO levels during start, taxi and take off is on average 35 ppm (parts per million). Run up pushes that number up to >50 ppm. I have seen numbers as high as 100 ppm, especially on landing and at shut down. I have done all of the exhaust and some of the cockpit seal modifications recommended. There is not a real problem during flight. I have been seeing levels ranging from 2 to 5 ppm during cruise. That number changes significantly during maneuvers at high alpha.  During stalls, loops, Cuban 8’s ect., the number rises  to around 20-30 ppm.   

The levels are measured with a  data logging portable professional CO monitor from Draegar. I have measured the level at waist level, chest level, and at nose level. With the canopy open and closed during start, taxi, run up, TO, climb out, aerobatics, formation flight, landing, taxi, and run up for shutdown. The  problem is the worst on the ground and as already stated, during slow or high alpha (angle of attach) flight.   

I have also measured the levels outside the cockpit beginning at the wing root, one half the way up the side of the fuselage, at the canopy rail and at the top of the canopy during idle. I have not measured it during flight since my probe will not stay in place! The level rises significantly as you go from the top of the canopy down to the wing root.  

As a warning, you definitely do not want to taxi the 50 with the canopy closed or sit idling for a period of time with the it closed. I saw numbers climbing to over 100 ppm while idling for about 10 minutes waiting for a rain shower to pass over. I was literally sitting in a bath of CO!  

OSHA (US) defines exposure as  based on concentration inspired over time exposed. PMEL is the permissible exposure limit and MEL is maximum exposure limit. These limits are defined as the average exposure for a worker in the environment for 8 hours a day and 40 hours per week. PMEL is set at 35 ppm and MEL is set at 50 ppm. That is given for a worker working at 1 ATM (atmosphere), the equivalent of sea level.   

As aviators or divers for that matter, the Atmospheric pressure decreases as we climb in altitude, as does our inspired Oxygen concentration. The problem is that CO binds to Hb (hemoglobin) 200 times stronger than Oxygen. Where the release time from Hb by oxygen is on the order of milliseconds, CO hangs on for hours. So you have a relative hypoxia at altitude as compared to the pilot that is breathing air free of CO. (As a technicality, for the divers, the Atmospheric pressure increases as you descend in depth). The physiology of the CO induced hypoxia is essentially the same for both the aviator and the diver but not technically.  

My question is, what is such a system worth to you? I have an estimate on what it will cost to produce the basic system. It will be more if certain bells and whistles are included like the aviator’s 02 mask, bayonet fittings for the mask/helmet and  on board  in line CO and 02 monitor (not cheap)   

$ (US) 500-1000  

$1000-1500  

$1500-2000  

$2000-2500  

$2500-3000  

$3000-3500  

$3500-4000  

I know this is an open ended  question but.. I need to know if it is worth going forward with this project.   

I have a scuba system that I have designed that I currently use with the 50.  I can make available  if you want to go that route. It entails using a scuba tank that has to be refilled after each flight. That can be a bit of a pain as well as there is the issue of increased weight.  

I have investigated the cost of instillation of a diluter demand 02 system also. The cheapest that I can get the components for that system is $3300. Those are mil surplus that have been remanufactured. The problem with the diluter demand system is that you are still breathing ambient air which is contaminated with CO. I have talked to the manufacturer of the new systems (CRU-121) as to acquisition cost for their products. They want $10000 for their consol and it is only sold to military contractors for use in (active duty) military aircraft. They will not sell the product to a civilian (non DOD contractor). That system does not include any of the additional components like, the mask, tubing, fittings, or 02 tank. Seems they want no part of the liability that goes with dealing with the civilian world. Our litigious societies strike again.  

Thanks for your time and feed back in advance.  

Doc

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HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Sun Aug 26, 2007 8:00 am Post subject: Re: Carbon Monoxide Filters

Doc,



I appreciate you  looking into this. I know after a long day of flying, I have a bit of a headache. 



Has anyone looked at the exhaust system and what can be done there? Extending the pipes back a few feet or something along those lines? There are other airplanes with similar set-ups as ours that don't have the problems we do...or they are ignorant to it.

viperdoc(at)mindspring.co
Guest

Posted: Sun Aug 26, 2007 10:09 am Post subject: Carbon Monoxide Filters

Craig did a lot of this on the exhaust system already. Replacing the steel

wraps on the exhaust sections is one place to begin. Sealing the oil cooler

on the inside of the fuselage. I used the firewall pad from Wag Aero. That

did not lower the CO levels in the 50 though. I think the open tail wheel

opening is a major culprit for why the levels are still up. 

If you noticed, your face may be flushed at the end of 3 sorties along with

that headache. Dehydration is one reason for the headache also. As well as

that washed out feeling especially if the temperature is in the 90-100's

too. 

Since I have been flying the 50 with the scuba system, I have not been

nearly as tired after a sortie. I use it for all ground ops and acro.

Otherwise the system does not have enough air for a full hour. The problem

is that it has to be refilled at the end of each sortie. I have looked at

the new spun aluminum kevalar wrapped tanks. They hold 5000 psi (roughly 1.2

hours) and are light, 39 lbs, but are expensive at ~$900. Yes you can get

used ones on ebay for less but again is on ebay because it failed it's

hydro?

Doc 



--

cpayne(at)joimail.com
Guest

Posted: Mon Aug 27, 2007 2:38 am Post subject: Carbon Monoxide Filters

I believe that there may be another answer to CO-contamination for *many* of the flight and ground conditions that we normally encounter in a flight. However, this solution would add weight and look ugly. On a CJ-6, anything that looked Ugly would stand out like a turd in a punch bowl. On a Yak, well....maybe you wouldn't notice as much :>)

  

 What I'm talking about would look a little like the Canadian Harvard with exhaust tube running back along the fuselage. In case of the Yak/CJ, the tubes would not go through the cowl but exit out the bottom through a cowl bump that allows removal of the cowl without messing with the exhaust tubes. The tubes would run along  the fuselage to a point under the wing root. Yes, weight would be added and it would be noticable (on a CJ anyway)

  

 With such a system, gases would be expelled past the point of airflow over the wing, and away from the wheel well area on CJ's. However, there would still be problems in certain acro conditions of tumbles, inverted spins, tail slides and the other things I don't do anyway.

  

  

 Craig Payne

 cpayne(at)joimail.com (cpayne(at)joimail.com)

  

  

 

  [quote][b]

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Mon Aug 27, 2007 4:58 am Post subject: Re: Carbon Monoxide Filters

Craig,



You need to stay out of my head. I have an airborne picture of me in my airplane hanging on the wall in the man cave and was looking over the lines of the -50 and thinking the EXACT same thing. 



There is someone out there smarter than me who can figure iy out.

viperdoc(at)mindspring.co
Guest

Posted: Mon Aug 27, 2007 5:55 am Post subject: Carbon Monoxide Filters

One other thing on the SNJ,Harvard,T-6 is that the their exhaust ring is sleeved and slotted. So one segment fits into the other segment so there is minimal leakage around the connections. The last T-6 or Harvard I looked at, the exhaust was a single ring that exited on the  side of the cowling so exhaust flows over the wing not under it.  

I would be curious as to what values Tj is seeing with his Tarantula exhaust on his 50. It sends the exhaust gases over the wing. It certainly decreases the collective flow effect under the tail venting gas up into the empennage at the strut opening on the 50. Remember, the Bernoulli effect of the prop wash accelerating over the top of the canopy causing a high pressure on top of the canopy and a low pressure area in the cockpit. The base effect is increase suction of gases into the cockpit. You can see this in the smokers at high alpha. Their cockpits are full of smoke. Why there is a relative low inside the cockpit and the gas is in trained into that low.  

Doc  

       

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Craig Payne

 Sent: Monday, August 27, 2007 5:37 AM

 To: yak-list

 Subject: Re: Carbon Monoxide Filters  

  

  

     

I believe that there may be another answer to CO-contamination for *many* of the flight and ground conditions that we normally encounter in a flight. However, this solution would add weight and look ugly. On a CJ-6, anything that looked Ugly would stand out like a turd in a punch bowl. On a Yak, well....maybe you wouldn't notice as much :>)  

    

   

    

What I'm talking about would look a little like the Canadian Harvard with exhaust tube running back along the fuselage. In case of the Yak/CJ, the tubes would not go through the cowl but exit out the bottom through a cowl bump that allows removal of the cowl without messing with the exhaust tubes. The tubes would run along  the fuselage to a point under the wing root. Yes, weight would be added and it would be noticable (on a CJ anyway)  

    

   

    

With such a system, gases would be expelled past the point of airflow over the wing, and away from the wheel well area on CJ's. However, there would still be problems in certain acro conditions of tumbles, inverted spins, tail slides and the other things I don't do anyway.  

    

   

    

   

    

Craig Payne  

    

cpayne(at)joimail.com (cpayne(at)joimail.com)  

    

   

    

   

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        [quote][b]

tjyak50

Joined: 31 May 2007
Posts: 81
Location: Phoenix, AZ

Posted: Tue Aug 28, 2007 8:16 am Post subject: Re: Carbon Monoxide Filters

The "Barkmaster" exhaust on my 50 exits out the side of the cowling, and didn't change the CO problem in the cockpit at all.



My airplane also has an enclosed cockpit and I can clearly see (with smoke on) that the exhaust / smoke comes from the back of the airplane, forward to the cabin through my aft bulkheads vents.



In flight, if I close my canopy and open the vent at the front of the Yak 50 windscreen it tends to pressurize the cockpit and the exhaust / smoke is reduced 90%.



Tj

viperdoc(at)mindspring.co
Guest

Posted: Tue Aug 28, 2007 10:28 am Post subject: Carbon Monoxide Filters

Tj, Thanks. You have just confirmed my theory on the 50. One of our big

culprits is that hole our tail wheel sticks out of.

To answer the other questions of just fixing the exhaust problem. I think it

will take extending the exhaust stacks all the way to the rear of the AC. 

Remember what I said in my post earlier. I measured the CO concentrations at

the wing root (on top) and on bottom along with up the side of outside of

the  cockpit to the top of the canopy bow. The lowest (key word lowest) was

at the top of the canopy. The highest was at the wing root. Almost equal to

the bottom of the wing root. Now why would that be?

Guys, you are sitting in a vat of CO on the ground.

My probable next move will be to put NACA ducts on the top of the fuselage

just aft of the firewall to get fresh air to pass through the catalyst on

its way to my aviator's mask. 

I guess I will do some further testing measuring the CO levels out the wing

to the tip while  the YAK is idling on the ramp.

Doc 



--

dabear(at)damned.org
Guest

Posted: Tue Aug 28, 2007 11:35 am Post subject: Carbon Monoxide Filters

Doc,



I was going to put the NACA duct on the top of the tail.  That would put 

it out of the way of the CO/smoke stream in all but the highest of 

alpha.  Then run the duct into the front and rear of the cockpit (not 

using a mask) to pressurize the cockpit. 



DaBear

Roger Kemp wrote:

[quote] 



 Tj, Thanks. You have just confirmed my theory on the 50. One of our big

 culprits is that hole our tail wheel sticks out of.

 To answer the other questions of just fixing the exhaust problem. I think it

 will take extending the exhaust stacks all the way to the rear of the AC. 

 Remember what I said in my post earlier. I measured the CO concentrations at

 the wing root (on top) and on bottom along with up the side of outside of

 the  cockpit to the top of the canopy bow. The lowest (key word lowest) was

 at the top of the canopy. The highest was at the wing root. Almost equal to

 the bottom of the wing root. Now why would that be?

 Guys, you are sitting in a vat of CO on the ground.

 My probable next move will be to put NACA ducts on the top of the fuselage

 just aft of the firewall to get fresh air to pass through the catalyst on

 its way to my aviator's mask. 

 I guess I will do some further testing measuring the CO levels out the wing

 to the tip while  the YAK is idling on the ramp.

 Doc 



 --

viperdoc(at)mindspring.co
Guest

Posted: Tue Aug 28, 2007 12:30 pm Post subject: Carbon Monoxide Filters

DaBear,

You have a TW if my failing memory serves correct? 

What I will plan to do with the next round of measurements is check the CO

at the top of the vertical stab as I check the levels along the wing.

A little CO is better than a lot but none is better than sum. Remember about

what I said about the decrease in the partial pressure of 02 as we climb in

altitude and the fact that CO that bound to your Hb on the ground will

potentiate the effect of hypemic hypoxia at altitude. 

My theory for putting the NACA duct as near to the top back side of the

cowling at the firewall was; it is the highest point on the aircraft when

dragging its' tail and the nearest to prop for airflow. When looking at the

aircraft with smoke turned on while idling on the ground, the smoke does not

swirl up over that part of the cowling but it does eddy behind the wings and

up over the tail. 

Any other thoughts on NACA duct placement? I think for the 50 and the TD,

sealing that bulkhead in front of the tail wheel strut would be of major

benefit in decreasing CO being entrained through that spot.

Doc



--

dabear(at)damned.org
Guest

Posted: Tue Aug 28, 2007 2:42 pm Post subject: Carbon Monoxide Filters

Doc,



Haven't taken the plunge on a TW.  I still have the nosedragger 

Yak-Chang (CJ with the M14).   Hence why I thought the top of the tail 

would be good.  I realized from your post, that you are probably right 

that for a TW a great place would be top back side of the cowling.



I'm wondering if I would do anything to help airflow with a ducted fan 

in the NACA duct during ground ops? 



While I like the idea of adding O2 for cross country flight over 6-8k.  

I'm not thrilled with the idea of a mask or the associated microphone 

issues.



Dabear



Roger Kemp wrote:

[quote] 



 DaBear,

 You have a TW if my failing memory serves correct? 

 What I will plan to do with the next round of measurements is check the CO

 at the top of the vertical stab as I check the levels along the wing.

 A little CO is better than a lot but none is better than sum. Remember about

 what I said about the decrease in the partial pressure of 02 as we climb in

 altitude and the fact that CO that bound to your Hb on the ground will

 potentiate the effect of hypemic hypoxia at altitude. 

 My theory for putting the NACA duct as near to the top back side of the

 cowling at the firewall was; it is the highest point on the aircraft when

 dragging its' tail and the nearest to prop for airflow. When looking at the

 aircraft with smoke turned on while idling on the ground, the smoke does not

 swirl up over that part of the cowling but it does eddy behind the wings and

 up over the tail. 

 Any other thoughts on NACA duct placement? I think for the 50 and the TD,

 sealing that bulkhead in front of the tail wheel strut would be of major

 benefit in decreasing CO being entrained through that spot.

 Doc



 --

viperdoc(at)mindspring.co
Guest

Posted: Tue Aug 28, 2007 6:10 pm Post subject: Carbon Monoxide Filters

DaBear,

Copy. Putting the NACA duct on the top of the tail probably is a idea as

long as it does not interfere with the structural integrity of the vertical

stab. I believe BJ Kenmore put a NACA duct in front of the windscreen.

Doc



--

dsavarese(at)elmore.rr.co
Guest

Posted: Wed Aug 29, 2007 4:59 am Post subject: Carbon Monoxide Filters

Actually, BJ put his NACA duct just below and on the right side of the front 

canopy.

Dennis



---

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Wed Aug 29, 2007 6:25 pm Post subject: Re: Carbon Monoxide Filters

The ass end of my airplane is up in the air so I will look at what it would take to prevent CO from coming in. Maybe a cover for the bulkhead just inside the tailwheel inspection panel? Maybe a boot over the thing? Maybe some sort of external "device" that diverts air away. Something small as to not affect the handling qualities of the airplane.

viperdoc(at)mindspring.co
Guest

Posted: Wed Aug 29, 2007 6:42 pm Post subject: Carbon Monoxide Filters

Go simple. Go for the ceconite bulkhead cover.

Doc



--

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