Part 1

[Transcriber's Note:

Typographical errors (such as "COMAT" appearing for "COMBAT" in the title) and punctuation inconsistencies have been retained. The goal has been to provide a historically accurate representation of the original 1944 publication.]

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NOTES ON THE USE OF OXYGEN EQUIPMENT IN THE B-17, B-24, & B-29 FOR COMAT CREWS

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THIS PUBLICATION MAY BE USED BY PERSONNEL RENDERING SERVICE TO THE UNITED STATES OR ITS ALLIES

Paragraph 5.d. of Army Regulation 380-5 relative to the handling of "restricted" printed matter is quoted below.

"d. Dissemination of restricted matter.--The information contained in restricted documents and the essential characteristics of restricted material may be given to any person known to be in the service of the United States and to persons of undoubted loyalty and discretion who are cooperating in Government work, but will not be communicated to the public or to the press except by authorized military public relations agencies."

RESTRICTED

FOREWORD

These notes were originally intended as a source of general reference concerning OXYGEN EQUIPMENT AND ITS USE by members of crews of the B-17 and B-24 heavy bomber. With the advent of the B-29 as a combat bomber, the section on THE B-29 AT HIGH ALTITUDE (Page ) was added to supply certain specialized information concerning this ship. Every B-29 crew member should be familiar with the INTRODUCTION and the section on THE DEMAND OXYGEN SYSTEM as well as this specialized information. The subject matter is presented from a PRACTICAL point of view, based upon actual experiences encountered on altitude missions. Detailed information on oxygen equipment may be found in the following TECHNICAL ORDERS.

03-50-1 Use of Oxygen and Oxygen Equipment. 03-50A-5 Type A-12 Demand Oxygen Regulator (Pioneer). 03-50A-8 Type A-12 Demand Oxygen Regulator (Airco). 03-50B-1 Type A-10 Revised Oxygen Mask. 03-50B-6 Type A-14 Demand Oxygen Mask. 03-50C-3 Low Pressure Oxygen Cylinders. 03-50D-1 Oxygen Pressure Signal Assembly. 03-50D-2 Oxygen Flow Indicator Type A-1. 03-50D-4 Oxygen Flow Indicator Type A-3. 03-50D-5 Oxygen Pressure Gage Type K-1.

INDEX

Auto-Mix 17 Ceiling, effect of oxygen on 3 Dangers with oxygen 50 Demand oxygen system 7 Demand type masks 8 Duration of oxygen supply B-17 38 B-24 44 Method of computing 40 Emergency valve 19 Explosive Decompression 61 Flow indicator 32 Hazards of oxygen-lack 1 Leaks in oxygen lines 49 Leaks in regulator 11 Mask, Demand Fitting to face 9 Technic, at altitude 13 Testing for leaks 10 Mask-Regulator connection 16 Night Vision 2 Oxygen cylinders 37 Oxygen deficiency at altitude 3 Oxygen installation, Servicing of 47 Oxygen discipline 4 Oxygen systems B-17 36 B-24 43 B-29 57 Oxygen systems, diagrams of B-17 38 B-24 47A B-29 60 Oxygen equipment, check of 34 Portable oxygen equipment 20 Precautions with demand system 34 Passing out at altitude 51 Pressure Cabins, B-29 56 Regulator, Demand A-12 17 A-13 20 Regulator hose clip 16 Revival of passout victim 51 Servicing oxygen installations 47 Signal assembly 32 Sniff-tester 11 Testing for mask leak 10 The B-29 at High Altitude 53 Walk-around bottle 20 Walk-around bottle Uses of 20 Large, for engineer 25 When to use oxygen 1

INTRODUCTION

As a member of a heavy bomber team, in combat you will be living and fighting in a world where man has no business--from three to six miles above the environment for which nature designed you.

Successful and effective operation of combat crews at altitudes in excess of 15,000 feet requires that EVERY crew member be familiar with altitude problems. You must be so thoroughly familiar with your oxygen equipment that you will use it PROPERLY without giving it a thought. The time to acquire this experience is during operational training--not after you have pulled several boners in combat.

Through long hours of tiring training you have developed superior judgment, ability to make decisions quickly, and efficiently in firing and in other duties. Most of your training has been confined to relatively low altitudes in a relatively "normal" environment. Now you are going to continue this training "upstairs". To maintain the superiority and efficiency you possess OXYGEN MUST BE USED above 10,000 feet. Above 18,000 feet oxygen must be used to maintain consciousness and life itself.

WHEN SHOULD FLYERS USE OXYGEN?

(1) When wounded, especially with injuries accompanied by hemorrhage or shock.

(2) Above 10,000 feet on day missions, both in training and combat.

(3) From ground up on all night missions. (a) To prevent night blindness. (b) Night vision impaired early and to a marked degree at comparatively low altitude.

HAZARD OF OXYGEN-LACK

(1) At 12,000 to 15,000 feet (several hours): fatigue, drowsiness, headache.

(2) At 15,000 to 18,000 feet (½ to 1 hour): False sense of well being Overconfidence Narrowing of field of attention Faulty reasoning Poor judgement Loss of self-criticism Clumsy Blurring and double vision Decreased hearing Poor memory May pass out

(3) Above 18,000 feet: Symptoms come on faster Loss of muscle control Loss of awareness of lapse of time Loss of judgment and self-criticism Loss of memory and ability to think Loss of vision and hearing Purposeless movements, repeated over and over Emotional outbursts--hysteria, crying, laughing, anger Loss of consciousness eventually: at 26,000 feet 4 to 6 minutes at 28,000 feet 2 to 4 minutes at 30,000 feet 1 to 2 minutes at 38,000 feet 30 seconds or less The above varies with different individuals.

(4) Loss of night vision. Night vision is reduced to one-half at 12,000 feet without oxygen. Breathing oxygen restores it to normal.

(5) Breathing oxygen raises your ceiling.

ALTITUDE %OXYGEN EQUIVALENT FEET BREATHED LEVEL (feet) 18,000 60 ground 26,000 85 ground 30,000 100 ground 33,000 100 8,000 38,000 100 12,000 44,000 100 22,000

REASONS FOR OXYGEN DEFICIENCY AT ALTITUDE

(1) Inadequate supply for the mission. The low pressure oxygen system in the B-17 and B-24 is fully charged to a capacity of 450 pounds per square inch. This supply should last 7 to 9 hours, depending on activity of the crew members (Auto-Mix "ON").

(2) Oxygen supply exhausted by leaks in oxygen lines or cylinders.

(3) Flyer getting insufficient oxygen:

(a) Attempts to do excessively hard work.

(b) Mask leak: Improper fit; frozen exhaust valve; holes in mask or hose; growth of stubby beard.

(c) Leak around gasket between mask-regulator connection.

(d) Loose connections where supply hose connects to regulator.

(e) Freezing of moist oxygen at extremely low temperature.

(f) Obstruction of openings in regulator.

(g) Hole in rubber diaphragm in regulator.

(4) Breathing too deeply may produce a partial vacuum inside mask causing air to leak in from bottom or sides. BREATHE NATURALLY.

5 Don't expect to get oxygen from an empty walk-around bottle. If not fully charged, the bottle may last only a minute or two.

(6) Improper use of walk-around equipment.

OXYGEN DISCIPLINE

It is mandatory that every member of a heavy combat crew be highly trained in oxygen discipline. It is urged that oxygen "drill" be practiced by ALL crew members for at least 15 minutes on routine training flights before altitude missions are ever undertaken. Practice using and re-filling the walk-around bottle at various stations. Practice changing masks (page 12) and become expert at using oxygen from emergency sources (page 27). Practice reviving some crewmate who has supposedly passed out from oxygen lack. Practice going to your escape hatch on a walk-around bottle with parachute in place. Practice all emergencies that may arise some day in combat and when they arise they won't be emergencies.

The following responsibilities will fall upon every member of a combat crew. The airplane commander should satisfy himself that the following points are observed or provided for:

(1) Fitting of the crew with masks, (page 9). Periodical check of masks and mask fit.

(2) All crew members are familiar with hazards of oxygen-lack at altitude. (page 1).

(3) See that all crew members are drilled in "precautions with the demand system." (page 19).

(4) Be sure that ALL crew members realize the danger of mixing oil and oxygen. (page 50).

(5) Be able to compute oxygen duration in different systems on ship (pages 39 & 46).

(6) PRE-FLIGHT CHECK OF OXYGEN EQUIPMENT.

(a) Pressure in different systems.

(b) Be able to charge oxygen system if necessary. (page 47).

(c) Check regulators for proper setting (auto-mix), properly working diaphragm, hose-regulator connection, emergency valve OFF.

(d) Check EACH station for possible oxygen deficiency at altitude, (page 3).

(e) Check portable oxygen equipment, regulator diaphragm, and oxygen supply in bottles, see that regulators are working properly.

(f) Check all recharger hose valves for sluggish or sticking valves (page 20).

(7) Know how to re-distribute crew members to stations where oxygen is available if part of supply is lost. (pages 41 & 45).

(8) Someone to be able to find and repair a leak in oxygen lines. (page 49).

(9) Frequently check condition of crew members during flight. See that one crew member checks on a fellow crewmate when practicable. Check every 10-15 minutes above 20,000 feet. Co-Pilot can help in this regard.

(10) All crew members understand principles of reviving a crew member unconscious from oxygen lack. (page 51).

(11) Report to crew chief and personal equipment officer _on landing_ any and all faulty oxygen equipment. Make sure repairs to such equipment have been made before next flight.

THE DEMAND OXYGEN SYSTEM

The "demand" oxygen system in your ship insures a fully adequate oxygen supply except under the most extreme conditions. It was developed to supply you, AUTOMATICALLY, as much oxygen as you need when you need it--at all altitudes and under all conditions.

The DEMAND OXYGEN SYSTEM consists of the following:

(1) Demand type mask.

(2) Mask to regulator tubing.

(3) Demand type regulator (A-12).

(4) Portable recharging hose (for filling walk-around bottles

(5) Portable equipment: (a) A-4 Cylinder with A-13 demand regulator. (b) D-2 cylinder with A-13 regulator.

(6) A panel containing: a flow indicator an oxygen pressure gauge

(7) Cylinders containing breathing oxygen.

DEMAND TYPE MASKS

Styles: A-10A and A-14

The A-10 mask is obsolete.

The A-10 revised mask is obsoete.

The A-14 mask is standard issue for staging and combat areas, and operational or replacement training schools.

The A-10-A mask is used in training where sufficient A-14 masks are not available.

Both the A-10-A and the A-14 masks are suspended from the summer and winter flying helmets.

NOTE: It is important that AERIAL GUNNERS obtain a properly fitting mask, fit to both summer and winter helmets at the first station available. Because of the extreme cold to which gunners are subjected under combat conditions, you MUST learn to remove and replace the mask quickly and accurately WEARING HEAVY GLOVES. It is not easy to manipulate a mask or unjam a .50 cal. gun with numb fingers in heavy flying gloves. PRACTICE these things on every training flight with gloves ON.

FITTING THE MASK TO THE FACE -- There are two considerations in obtaining a proper fit: (1) An _AIR-TIGHT SEAL_ of mask to face. (2) Comfort of fit without undue pressure.

The A-10-A and A-14 masks come in three sizes. Roughly, 60% of flyers will require the STANDARD (medium) size mask, 30% the LARGE mask, and the remaining 10% the SMALLER sizes. General instructions concerning fitting are.

(1) Suspension points on both summer and winter helmets must be determined INDIVIDUALLY on each flyer. This is a job for your squadron personal equipment officer or the group aviation physiologist or his trained assistant.

(2) It is important that the mask be suspended _high_ on the face, sealing to the boney portion of the nose and cheek bones and NOT the soft tissues. Otherwise you'll get a leak or a "clothespin on the nose" effect from pressure of the nose wire.

NOTE:

(a) Be sure the regulator hose clip or the clip on the walk-around bottle is clipped high enough on your clothing to remove all tension from mask hose--otherwise the mask will be pulled down on the face and will leak outside air.

(b) Above 25,000 feet with the temperature 20 degrees and lower, the tissues of the face contract and the rubber mask loses its pliability. Under these conditions, the mask tends to fall away from the face and it becomes necessary to SHORTEN THE UPPER SUSPENSION STRAPS. On returning to warmer altitudes, these must be loosened again to avoid discomfort from a too tightly fitting mask. (Applies chiefly to gunners).

(3) Excessive beard stubble will hold the mask away from the face and cause leak around the jaws.

(4) See page 35 for care of mask.

(5) TESTING FOR LEAKS -- Holding the thumb over the end of the mask tube (rapid disconnect) and inhaling GENTLY should cause the mask to collapse on the face. The most common place for a leak is alongside the bridge of the nose. The actual site of leak is determined by putting finger-point pressure beside the nose and over the cheek bones, one point at a time. The nose wire is then re-adjusted to cause pressure at this point. Be sure the mask is high enough on the face and on the bridge of the nose. If the seal is still below the boney portion of the nose try the next largest size mask.

(6) "SNIFF-TESTER" -- An effective "sniff-tester" for detecting small leaks can be obtained as follows: Obtain one of the commercial nasal inhalers - Benzedrine, Vick's, Penetro (or metal tube of comparable size). Cut off the end ordinarily inserted into the nose flush with the barrel of the container, and remove contents. Fit barrel with an airtight cork stopper. Straighten a paper clip or take a piece of wire of similar gage, cut to 2½ inch length, and drive one end firmly into lower side of cork stopper. Fashion other end of wire into a 1/4 inch fish hook bend. Make a ball of cotton or tightly wrapped gauze, ½ inch in diameter, and attach to bent end of wire. Soak the cotton or gauze, in oil of peppermint or oil of cloves (obtained from squadron dentist or flight surgeon) and fit cork stopper, carrying the "sniff-tester" tightly into metal container. To "sniff-test", remove the stopper and hold the cotton plug on both sides of the nose at the top of the mask (eyes closed). Inhale gently with the mask hose blocked. A leak is present if the contents of the "sniff-tester" is detected. Rough as this test seems, it is very sensitive.

NOTE: The "sniff-tester" is also effective in testing the DEMAND REGULATOR for leaks. Put on mask. Fit snugly to face. Plug into regulator hose. Turn Auto-Mix (Air) Lever OFF. Hold sniff-tester close to regulator diaphragm and breathe normally several times. If the contents of the sniff-tester" are detected, the regulator has a leak.

TWO TYPES OF "SNIFF-TESTERS"

(A) Cotton pledget soaked with oil of peppermint.

(B) Benzedrine inhaler containing blotter soaked with oil of peppermint.

REMOVING MASK AT ALTITUDE -- There are many reasons why your oxygen mask will be removed above 20,000 feet. This has been responsible for countless "accidents" in heavy bomber crews IN advanced training and in combat. LEARN THE PROPER TECHNIC NOW, wearing heavy gloves. You can take your oxygen mask off at 30,000 feet and be as safe as you are on the ground, PROVIDING YOU HOLD YOUR BREATH and don't breathe the "thin" outside air. The following are a few of the reasons why you will remove your mask at high altitude. DON'T REMOVE YOUR GLOVES, for freezing occurs almost instantaneously and painlessly at temperatures of 30 below and lower.

(1) To wipe moisture from inside the mask at regular intervals -- for comfort and to prevent ice formation around exhaust valve.

NOTE: A puddle of condensed moisture lying over the flutter valve will render it useless. You will be warned of this; when you breathe out, the air from your mask comes out the top of the mask, fogging your goggles.

(2) To blow your nose. To help clear your ears on descent by holding nose and blowing (if necessary). To vomit if you get sick.

(3) To take nourishment and hot drinks on missions.

(4) To change masks.

TECHNIC -- NEVER breathe when mask is off face or is loosened from helmet. PRACTICE THIS with a mirror: (See Fig. 2, 3 & 4)

(1) Hold mask to face firmly with left hand.

(2) Disengage mask clip from helmet with right hand.

(3) Holding mask snugly in position with left hand, take 3 or 4 deep breaths of oxygen.

(4) Remove mask with left hand, HOLDING BREATH. The right hand is free to service mask, to blow nose or to administer food or drink. Hold mask in left hand.

(5) When you have to breathe, reapply mask to face making sure it is held snugly along sides of nose with index and middle finger of left hand, one on each side. of nose (hold mask in palm of hand with index and middle finger making a V, one on each side of the nose piece).

(6) Take 4 or 5 deep breaths from the mask and repeat #4. This procedure may be kept up indefinitely with complete safety, providing you DON'T BREATHE OUTSIDE AIR.

MASK TO REGULATOR CONNECTION (RAPID DISCONNECT)

IS THE RUBBER GASKET IN PLACE? Without the gasket an air-tight seal at this joint is impossible. Dangerous oxygen-lack will result above 24,000 feet. With a leak at this altitude serious mental and physical inefficiency will develop, even though you may not pass out. Above 28,000 feet you will quickly become punch drunk, and the pass-out will soon follow.

USE THE CLIP ON THE REGULATOR TUBING--It is there to remove tension on this connection which could (1) cause serious mask leak by pulling the mask down on the face, or (2) cause mask tubing to become disconnected. In combat these things would fail to attract your attention. Without warning you are first slap-happy and then drop unconscious.

THE RAPID DISCONNECT REQUIRES CONSTANT ATTENTION whether you are plugged into a fixed station or into a walk-around bottle. A pull of at least 12 pounds should be required to separate the male and female connection of the rapid disconnect. The security of the connection can be increased by spreading the groups at the tip of the male connection. (See diagram, pre-flight check, page 39).

CONNECTION OF HOSE TO REGULATOR IS NOT A SWIVEL JOINT--Above 24,000 feet the collar must be turned up tightly to prevent a dangerous leak of air.

Make sure that the regulator hose is wired securely to the goose neck on the regulator.

THE DEMAND (A-12) REGULATOR

In principle the demand regulator is a diaphragm-operated flow valve which is opened by the user's inspiration and closes automatically when the suction ceases. This gives you as much oxygen as you ask for. All you do is breathe. A short breath draws a short squirt of oxygen, while deep, rapid breathing brings forth large shots in rapid succession.

The regulator can be set to conserve oxygen, or to give you 100% oxygen, regardless of the altitude you are flying. This is governed by the position of the "Auto-Mix" (AIR) lever.

AUTO-MIX (AIR) "ON" (or NORMAL OXYGEN) is the position for routine use. This saves oxygen.

(1) Gives a mixture of air and oxygen:

10,000 feet -- approx. 30% oxygen 18,000 feet -- approx. 65% oxygen 26,000 feet -- approx. 85% oxygen 30,000 feet -- approx. 100% oxygen

Under the above conditions, so far as oxygen is concerned, you are at ground level.

(2) Use oxygen from ground level on night missions to prevent night blindness.

(3) Increased altitude increases oxygen supply AUTOMATICALLY.

(4) Percentage of oxygen delivered keeps you at ground level efficiency.

(5) Ships oxygen supply, charged to 450 pounds lasts 10 men from 7 to 9 hours. (20,000 to 30,000 feet).

AUTO-MIX (AIR) "OFF (or 100% oxygen) -- used when ordered by first pilot, and on special occasions.

(1) Gives 100% oxygen, on demand, regardless of altitude.

(2) Used on special occasions:

(a) To casualties suffering from: 1. Loss of blood. 2. Shock. 3. Passing out from oxygen lack (revived).

(b) Regulator not giving enough oxygen in "ON" position (blue finger nails-beginning to feel pleased with yourself).

(c) To avoid gas poisoning if you land in a gassed area without gas masks.

(d) To flush nitrogen gas from body fluids when going above 30,000 feet, helping to prevent bends.

(3) Ship's oxygen supply, charged to 450 pounds, lasts 6 hours or less.

THE "EMERGENCY" VALVE IS DANGEROUS -- it should be used with extreme caution. A whole system can be depleted of oxygen in an hour or less if the "emergency" is opened only a quarter of a turn. Emergency "ON" changes regulator into a constant flow system and wastes precious oxygen. Use only to revive an unconscious crew member or to check line to make sure it is clear. Always make sure that "Emergency" is TIGHTLY TURNED OFF before ship leaves the ground.

NOTE: Don't be confused by the difference in appearance of demand regulators manufactured by various companies (see Fig. 9). THEY ALL WORK THE SAME.

PORTABLE OXYGEN EQUIPMENT

A PORTABLE RECHARGER HOSE is available at every station in the ship. Every crew member should know their location so well that they can be located immediately, even on the darkest night. In addition, there is a long recharger hose for filling the ball turret oxygen cylinder. (B-17-F).

When drawing oxygen through a portable recharger the refiller valve must engage the filler nozzle TIGHTLY, otherwise oxygen leaks around the connection and is lost. The oxygen supply of an entire system has been wasted in this manner.

FREEZING or STICKING of refiller valve is not uncommon at extremely low temperatures. Always check this after refilling your walk-around. A stuck valve will quickly deplete the entire supply of oxygen in that system. If the valve is stuck plug in a walk-around bottle and leave it there.

USES OF THE WALK-AROUND BOTTLE -- (1) As an ACCESSORY REGULATOR -- the A-13 regulator on the walk-around bottle is a demand type regulator without the "auto-mix" feature. It gives 100% oxygen on inspiration regardless of the altitude. By connecting the walk-around bottle FIRMLY into the portable recharger valve, one has an extra source of oxygen at that particular station. As long as the oxygen gauge at the station registers oxygen pressure the user is assured a supply of pure oxygen ... his supply is coming directly from the system. Remember this when reviving a passed out crew mate in the waist in the vicinity of the ball turret--the long recharger hose used to charge the oxygen bottle on the ball turret can be plugged directly into a walk-around bottle attached to the unconscious crew member's mask.