Apollo Lunar Module Servometric Meter, measuring 4.5″ x 4″ x 1.25″, with a Honeywell parts tag on the back: "Indicator-Servometric, Mfr Part No. JG903A7, Series 54, Serial No. 119, Part No. LSC350-80167-15, Contract No. NAS 9-1100." The front panel is headed "MM Hg," with a range of 0-30 torr, the area from 0-7.6 marked in green to indicate safe levels of carbon dioxide. This indicator would have been situated on the right side of the Lunar Module's instrument panel, in the ECS (Environmental Control Subsystem) section, labeled "Part Press CO2." The test wiring harness remains intact, and the front panel has a plastic slipcover designed to protect the indicator's anti-reflectant coating during transit and handling. Includes the original plastic bag, a thick packet of Honeywell test data, and inspection paperwork dated April 1969. A note on the paperwork tells those who tested the meter to leave the test wiring in place for any future tests. In very fine condition.
The NASA publication Biomedical Results of Apollo (SP-368) discusses the carbon dioxide levels recorded throughout the Apollo program, making note of the safe range and the problems encountered during Apollo 13: 'The carbon dioxide levels recorded by sensors in the Command and Lunar Modules remained well below the limit of 1010.8 N/m2 (7.6 torr) except for the return flight of the Apollo 13 spacecraft. The Lunar Module environmental control system was used for approximately 83 hours on this mission, and the first lithium hydroxide cartridge was used for approximately 83 man-hours. During this time, the carbon dioxide level was permitted to increase to an indicated 1981.7 N/m2 (14.9 torr). Subsequently, four CM cartridges were used in a special arrangement devised and tested at the Lyndon B. Johnson Space Center during the mission. By using this arrangement of four lithium hydroxide cartridges, carbon dioxide levels were maintained between 13.3 and 239.4 N/m2 (0.1 and 1.8 torr).'
Terms and abbreviations used in our descriptions.