[Code of Federal Regulations]
[Title 40, Volume 30]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.315]

[Page 663-664]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1065_TEST PROCEDURES AND EQUIPMENT--Table of Contents
 
              Subpart D_Analyzer and Equipment Calibrations
 
Sec. 1065.315  Torque calibration.

    You must use one of two techniques to calibrate torque: the lever-
arm

[[Page 664]]

dead-weight or the transfer technique. You may use other techniques if 
you show they are equally accurate. The NIST ``true value'' torque is 
defined as the torque calculated by taking the product of an NIST 
traceable weight or force and a sufficiently accurate horizontal 
distance along a lever arm, corrected for the lever arm's hanging 
torque.
    (a) The lever-arm dead-weight technique involves placing known 
weights at a known horizontal distance from the torque-measuring 
device's center of rotation. You need two types of equipment:
    (1) Calibration weights. This technique requires at least six 
calibration weights for each range of torque-measuring device used. 
Equally space the weights and make sure each one is traceable to NIST 
weights. You also may use weights certified by a U.S. state government's 
bureau of weights and measures. If your laboratory is outside the U.S., 
see Sec. 1065.305 for information about using non-NIST standards. You 
may account for effects of changes in gravitational constant at the test 
site.
    (2) Lever arm. This technique also requires a lever arm at least 20 
inches long. Make sure the horizontal distance from the torque-
measurement device's centerline to the point where you apply the weight 
is accurate to within 0.10 inches. You must 
balance the arm or know its hanging torque to within 0.1 ft-lbs.
    (b) The transfer technique involves calibrating a master load cell 
(dynamometer case load cell). You may calibrate the master load cell 
with known calibration weights at known horizontal distances. Or you may 
use a hydraulically actuated, precalibrated, master load cell and then 
transfer this calibration to the device that measures the flywheel 
torque. The transfer technique involves three main steps:
    (1) Precalibrate a master load cell or calibrate it following 
paragraph (a)(1) of this section. Use known weights traceable to NIST 
with the lever arms specified in paragraph (b)(2) of this section. Run 
or vibrate the dynamometer during this calibration to reduce static 
hysteresis.
    (2) Use lever arms at least 20 inches long. The horizontal distances 
from the master load cell's centerline to the dynamometer's centerline 
and to the point where you apply weight or force must be accurate to 
within 0.10 inches. Balance the arms or know their 
net hanging torque to within 0.1 ft-lbs.
    (3) Transfer calibration from the case or master load cell to the 
torque-measuring device with the dynamometer operating at a constant 
speed. Calibrate the torque-measurement device's readout to the master 
load cell's torque readout at a minimum of six loads spaced about 
equally across the full useful ranges of both measurement devices. (Good 
engineering practice requires that both devices have about the same 
useful ranges of torque measurement.) Transfer the calibration so it 
meets the accuracy requirements in Sec. 1065.105(a)(2) for readouts 
from the torque-measurement device.