Metabolic simulation combustion chamber was developed as subsystem for breathing metabolic simulator. Entire system is used for evaluation of life support and resuscitation equipment. Metabolism subsystem simulates a human by consuming oxygen and producing carbon dioxide. Basic function is to simulate human metabolic range from rest to hard work

Bartlett, R. G.

Hendricks, C. M.

English

NASA Technical Reports Server

October 1972
	 B72-10658 
NASA TECH BRIEF 
NASA Headquarters 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Metabolic Simulation Chamber 
The problem: 
In evaluation of life support equipment, it is often 
necessary to simulate a range of metabolic rates that are 
identical to those of the human subjects. Simulation of 
metabolism involves the reproduction of air which is 
identical in chemical composition to that of the air 
exhaled by the humans. Advantages of simulated meta-
bolism compared with those of human subjects include a 
consistent performance, a rapid selection of desired 
metabolic rates, and use in environments which may be 
dangerous to humans.
Remote Flow 
Meter Sensors 
Remote Adjust 
Metering Valves 
Remote Control 
Solenoid Valves 
Manual
iegulators' 
Carbon 
Dioxide
The solution: 
A metabolic simulation combustion chamber has been 
developed as a subsystem for the breathing metabolic 
simulator (see Notes). The entire system is used in 
evaluation of life support and resuscitation equipment. 
How it's done: 
The metabolism subsystem, as shown in the figure, 
simulates a human by consuming oxygen and producing 
carbon dioxide. Its basic function involves oxidation of 
propane gas by air and addition of CO 2 in various 
Chamber4 
Heater
Chamber 
Thermocouple 
Adjustable 
Orifice
Radiant 
__ Pressure	 Cooler 
Monitor 
Accumulator
.
Output To
Bellows 
Input From Bellows 
Compressor 
Propane
(continued overleaf) 
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	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000657 2020-03-17T03:42:53+00:00Z
proportions to simulate human metabolic range from rest 
to hard work. 
In operation, the subsystem uses a quartz combustion 
chamber which is 30 cm (12 in.) long with a centered 
main body having a length of 15 cm (6 in.) and a 3.18 cm 
(1.25 in.) outside diameter. The chamber is connected to 
gas lines through flexible stainless steel vibration isolators 
and is surrounded by a two-piece insulated electrical 
heating element. Each half of the element requires 375 
watts and is energized continuously in normal operation. 
The incoming gases consist of propane, air, and carbon 
dioxide at a normal temperature and the desired ratio. 
This ratio is always sufficient to provide enough oxygen 
for complete propane oxidation. As the gases enter the 
chamber they are mixed by encountering the tubing 
segments, and as they progress through the chamber, their 
temperature is raised in excess of the normal propane 
ignition temperature of 741K (875°F). Normal opera-
tion, depending on flow rates, involves a temperature 
range of 978 to 1048K (1300 to 14250 F), as measured by 
a thermocouple located in the well at the output end, 
which completely oxidizes the propane. 
The metabolic simulation combustion chamber has 
several features. First, its design permits an external heater 
to maintain an internal temperature in excess of the 
normal propane ignition temperature over a wide range of 
gas flow rates. Thus, metabolic simulation is achieved over 
a wide CO2 /02
 ratio range simply by varying the input
CO2
 and the propane flow rates. And second, the design 
contains provision for a thermocouple to monitor temper-
ature within the combustion chamber. This permits 
remote verification of the desired temperature and also 
the use of a temperature safety monitor to automatically 
shut-off propane flow in the event that temperature falls 
below the preset nominal temperature of 811K 
(1000°F). 
Notes: 
1. Additional information is contained in the following 
Tech Briefs: B72-10657 (HQN-10766), B72-10659 
(HQN-1 0777), B72-10660 (HQN-10778), and 
B72-10661 (HQN-10779). 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
NASA Headquarters 
Code KT 
Washington, D. C. 20546 
Reference: B72-10658 
Patent status: 
NASA has decided not to apply for a patent. 
Source: R. G. Bartlett and C. M. Hendricks of

IBM Corp.
under contract to
NASA Headquarters
(HQN- 10776) 
B72-10658	 Category 05


Metabolic simulation chamber

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