[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.215]

[Page 705]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents
 
                    Subpart C_Measurement Instruments
 
Sec.  1065.215  Pressure transducers, temperature sensors, and dewpoint sensors.

    (a) Application. Use instruments as specified in this section to 
measure pressure, temperature, and dewpoint.
    (b) Component requirements. We recommend that you use pressure 
transducers, temperature sensors, and dewpoint sensors that meet the 
specifications in Table 1 of Sec.  1065.205. Note that your overall 
systems for measuring pressure, temperature, and dewpoint must meet the 
calibration and verifications in Sec.  1065.315.
    (c) Temperature. For PM-balance environments or other precision 
temperature measurements over a narrow temperature range, we recommend 
thermistors. For other applications we recommend thermocouples that are 
not grounded to the thermocouple sheath. You may use other temperature 
sensors, such as resistive temperature detectors (RTDs).
    (d) Pressure. Pressure transducers must be located in a temperature-
controlled environment, or they must compensate for temperature changes 
over their expected operating range. Transducer materials must be 
compatible with the fluid being measured. For atmospheric pressure or 
other precision pressure measurements, we recommend either capacitance-
type, quartz crystal, or laser-interferometer transducers. For other 
applications, we recommend either strain gage or capacitance-type 
pressure transducers. You may use other pressure-measurement 
instruments, such as manometers, where appropriate.
    (e) Dewpoint. For PM-stabilization environments, we recommend 
chilled-surface hygrometers. For other applications, we recommend thin-
film capacitance sensors. You may use other dewpoint sensors, such as a 
wet-bulb/dry-bulb psychrometer, where appropriate.

                        Flow-Related Measurements