How To Use Sigg Tourist Cook Set
FAQ - Carbon Monoxide and Stoves
This article was summarised from "Backpacking Equipment Buyer's Guide", 1978
by William Kemsley & the editors of Backpacker Magazine
Copyright � 1978 by Backpacker, Inc
Reproduced with acknowledgment to Backpacker Magazine
Send any comments to the maintainer Roger Caffin
 | Carbon Monoxide in TentsAuthors Joseph Kohler & Robert Wagner setting up a CO analyzer inside a tent to measure out carbon monoxide dangers of stoves. The tent was made of breathable nylon but pitched without rain fly. During the tests, the tent's rear vent was open & the tent entrance was zipped partially open. Afterward v minutes virtually stoves had filled the tent with dangerous quantities of carbon monoxide. The authors wrote every bit follows: |
While backpacking in New Hampshire's White Mountains last winter, four members of our political party of 12 complained of dizziness and nausea after supper. The symptoms were the aforementioned as every bit those associated with altitude sickness, only we were camped at merely 3400 feet. All four men felt fine the next morning, and the incident passed without explanation. Several months later nosotros found a small winter-stove and melt-kit combination at a low price at a local hardware store. We bought a stove and decided to endeavour it out by cooking lunch in an office at work. After 30 minutes, we noticed we felt dizzy and were experiencing mild headaches. We smelled combustion odors and decided to examination for carbon monoxide. Our suspicions were confirmed when we establish carbon monoxide levels of more 100 parts per million (ppm) near the stove. We recalled the complaints of the four men during our wintertime trip. Unlike the rest of the grouping, they had cooked supper inside their tent because of severe winds and a low temperature. We decided their discomfort probably had resulted from exposure to a loftier level of carbon monoxide produced by their mount stove.
Why Carbon Monoxide Is Unsafe.
Carbon monoxide (CO) is a colorless and virtually odorless gas that results from the incomplete combustion of hydrocarbons. In the body some of the blood�s haemoglobin that ordinarily would pick up oxygen in the lungs picks up CO instead, and so the amount of oxygen in the blood is reduced. The CO reacts with the haemoglobin to course carboxyhaemoglobin. The corporeality of carboxyhaemoglobin formed depends on the concentration of CO and the duration of exposure. Low amounts crusade headache, dizziness and nausea; loftier amounts cause coma and death. An increment in altitude increases the severity of the effects because of the depression oxygen saturation in one�s claret.
The Research
We decided to investigate the concentrations of CO produced in a tent past some common stoves. We used an uncoated nylon A-frame tent [in case it burnt downwards?]. Nosotros tested 8 stoves: Bleuet (butane), Gerry Mini (liquid propane gas), Gerry Mini Mark Two (1p gas), Primus Grasshopper (propane), Optimus 77A (methanol), Svea 123 (Coleman fuel), Optimus 111B (Coleman fuel) and MSR (Coleman fuel). The Svea 123 was tested with the Sigg Tourist Melt Kit, the Gerry Mini stoves in the Gerry Tourist Cookset and lone, and the Optimus 77A in the cookset sold with the stove, All stoves were clean and in excellent operating status.
How the Stoves Were Tested.
An identical procedure was followed in all experiments. Stoves were centered 18 inches from the front archway of the tent. Sampling probes were placed 28 inches from the eye of the front archway at a height of 24 inches, representative of the caput level of a person cooking. Tubing connected the probes to two CO analyzers. Both analyzers were calibrated and checked against each other at levels below 100 ppm. Preliminary tests were conducted outdoors on a calm, lx F day; extensive testing was done in a well-ventilated laboratory at 60 F. The tent was pitched normally, without its wing. The 9-inch circular vent in the rear was kept fully open up, and the front flap was zipped partly closed to grade a triangular opening measuring ten x 10 10 12 inches at the tent�southward noon. Clamps were placed on the attachment to ensure endmost to the same position in each experiment. Prior to each experiment, the analyzers were zeroed and calibrated, and background levels of CO were recorded. They measured a maximum of 5 ppm at the beginning of each test and never exceeded 8 ppm.
Three pints of h2o at 60 F were placed in a 2�-quart aluminum pan (Sigg). Each stove was started outside the tent. Every bit before long as it reached stable operating conditions it was placed within the tent in the position indicated. The pot was centered on the burner, the door was quickly zipped shut as far as the clamp stops, and timing started. Concentrations of CO were recorded at one-one-half or one minute intervals until the levels stabilized, The stoves were run for 15 minutes.
What the Tests Showed.
The CO concentrations produced past the Optimus 77A, the Gerry Mini (with and without the Gerry Tourist Cookset), the Optimus 111B and the MSR rose rapidly during the first few minutes, then stabilized when the rate of CO escaping from the tent became equal to rate of CO produced by the stoves. The final concentrations, shown in the graph below, ranged from 70 to 130 ppm. (The Gerry Mini in the Tourist Cookset might take produced higher levels, just the stove ran out of fuel). The CO concentrations produced by the Bleuet, the Primus Grasshopper and the Svea 123 with the Sigg Tourist Melt Kit rose at a slower charge per unit and stabilized at much lower levels � twenty to 25 ppm. The CO level produced by the Gerry Mini Marker Two had not stabilized when the run was terminated.
What caused the high concentrations?
Conspicuously, the greater the rate of production of CO, the college the final concentration in the tent. The charge per unit of CO product depended on 2 factors: the corporeality of fuel burnt by the stove and the degree of incomplete combustion. The output was determined hands by past the output of free energy: the Optimus 111B and MSR had high outputs; the Gerry Minis, the Optimus 77A and the Svea 123 had moderate outputs; and the Bleuet and Primus Grasshopper had lower outputs. And then we measured the degree of incomplete combustion by measuring the CO concentration very near each stove � by placing the probe from the ecolyzer close to the burner while the stove was operating without pans on its supports. Somewhat surprisingly we institute that the Optimus 111B and 77A, MSR and Gerry Minis did not produce a CO concentration as high as that at caput level inside the tent.
Then nosotros repeated the tests for incomplete combustion, this fourth dimension with pans of h2o placed on the stoves, and got quite different results. The concentrations of CO near the bottom of the pan were more than 200 ppm in every case except for the Svea 123 with the Sigg Melt Kit, which produced xxx ppm exactly as it had earlier when no pan was used. The only credible reason for high product past the other stoves was that the flame impinged on the pan. Nosotros decided the common cold pan surface acquired quenching (cooling) of the flame, which resulted in incomplete combustion. The flame of the Svea 123 however did not impinge on the pan. [Added past RNC: one combustion path is from carbon to carbon monoxide to carbon dioxide: interrupting the process can get out the CO unburnt.]
We raised the pans on several stoves. When flames no longer impinged on the pans CO concentrations dropped. Next we modified several stoves to prevent flame impingement and lower the amount of CO produced. The Optimus 111B was modified by replacing the pan supports with supports 25 mm longer. The pan support for the MSR stove was first raised 18 mm, then 25 mm. The short windscreen on the Gerry Tourist Cookset was replaced by the windscreen from the Sigg Cook Kit, which was xxx mm taller. The original experiments were repeated using the modified stoves. The CO levels produced by both 'Gerry' Minis with the modified cookset and the modified Optimus 111B were dramatically reduced and were well within rubber limits. The CO concentration produced by the MSR with the pot raised 3-quarters of an inch was reduced, only yet high; with the pot raised 25 mm the level was very low.
Conclusions
Information technology is apparent from our tests that several of the high-output stoves produce high levels of carbon monoxide in a partially vented, breathable nylon tent as a event of incomplete combustion caused by flame quenching. It is likely that most other high-output stoves would produce like levels and that fifty-fifty low-output stoves could produce loftier levels in a coated nylon tent. [Latter clause is doubtful if the low-output stoves are non producing much CO anyhow. RNC] Exposure to such levels of carbon monoxide probably is not unsafe at low altitudes although information technology may lead to discomfort. At altitudes above 10,000 feet, even so, carbon monoxide poses a potentially dangerous adventure by reducing the already low oxygen saturation of the claret. The effects would depend also on the functioning of the particular stove, the ventilation of the tent and the duration of cooking time.
Tables of Deadly Doses
Hither's How Much Carbon Dioxide The Stoves Gave Off. The curves on the chart bespeak incremental levels of carbon monoxide in the tent produced by the burning stoves. The Co measurements were taken at 1 minute intervals. The horizontal dotted line indicates the maximum level of carbon monoxide considered "safe" by the Amended Air Quality Human action of 1970 [35 ppm].
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When Pot Supports Were Raised
The authors institute that carbon monoxide dangers of stoves were reduced by raising stove pot supports 25 mm, loftier enough that the flame did not touch on the pot bottom. While it took slightly longer to boil a pot of water, the carbon monoxide emission was lowered to safer levels.
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Effects of Carbon Monoxide Poisoning
At sea level 97% of the haemoglobin in the blood is bound with oxygen as HbO2. Withal, carbon monoxide (CO) can combine with haemoglobin in the blood to form carboxyhaemoglobin (HbCO), and this reduces the ability of the claret to transport oxygen. The resulting condition is termed hypoxia. Hypoxia tin too be caused by depression oxygen pressure at high altitudes or by sure diseases. The amount of HbCO formed depends on the concentration of CO, the duration of exposure and the charge per unit of breathing. The physiological furnishings of hypoxia increase progressively as the level of HbCO increases and the level of HbO2 decreases. The beginning symptoms announced at HbOii levels between 95% and 92% saturation, when an private may begin to experience improvement [sic, but probably should be 'degradation'.] in fourth dimension interval discrimination, visual acuity and other psychomotor responses. The symptoms become more noticeable as the HbOii level drops to ninety% saturation, where the individual may experience drowsiness, lassitude and mental fatigue. At 85% saturation, headache, occasional nausea and euphoria may experienced. The symptoms intensify and are dominated by a throbbing headache as the concentration of HbOtwo drops to 80% saturation. Vomiting and plummet occur at 70% saturation, coma at 60% and expiry at forty%. The ambient air quality standards as legislated past the 1970 Amended Air Quality Act limit the maximum average concentration of CO for a 1-hour exposure to 35 ppm, or an HbOtwo saturation level of 95.25%.
As an example, consider two winter mountaineers camped at a low elevation in an A-frame tent. Let�due south say they spend two hours melting snow, boiling water and cooking, and that this exposes them to approximately 100 ppm CO from the stove. This would upshot in HbCO levels of 5%. The HbO2 level in their blood would be 92% (the normal 97% minus the 5% tied up as HbCO). The mountaineers might feel unpleasant and experience some damage in visual acuity and other psychomotor responses merely would exist in no real danger.
Still, the effects of animate CO increase dramatically at college altitudes. Every bit distance increases, atmospheric pressure decreases and oxygen saturation in the blood decreases. The post-obit table shows the oxygen saturation at various altitudes for a person breathing pure air.
| Altitude (feet) | Percent of 02 Saturation |
|---|---|
| 0 | 97% |
| 5,000 | 95% |
| 10,000 | 90% |
| fifteen,000 | 83% |
| twenty,000 | 70% |
Since both distance and CO reduce the oxygen saturation of the claret, their effects are approximately additive. Suppose our winter mountaineers cook in their tent at an pinnacle of 5,000 feet, instead. The HbO2 saturation in their blood would be 95% (the normal amount at five,000 feet) minus the five% reduction caused past the stove, or 90%. They would experience drowsiness, lassitude and mental fatigue. At 10,000 feet the mountaineers� HbO2 levels would be 85% saturation. Headache, nausea and euphoria could ensue, and they would be in some danger. At altitudes higher than x,000 feet, exposure to levels of CO becomes very unsafe. At altitudes of 17,000 anxiety, the mountaineers could vomit and plummet. These effects represent what typical mountaineers might experience under the atmospheric condition indicated, but they might vary considerably from one individual to another depending on physical condition, acclimatization to distance and corporeality of practice.
Source: https://www.bushwalkingnsw.org.au/clubsites/FAQ/FAQ_Monoxide.htm
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