[Code of Federal Regulations]

[Title 40, Volume 31]

[Revised as of July 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 40CFR1065.220]



[Page 704-705]

 

                   TITLE 40--PROTECTION OF ENVIRONMENT

 

         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

 

PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents

 

                    Subpart C_Measurement Instruments

 

Sec.  1065.220  Fuel flow meter.



    (a) Application. You may use fuel flow in combination with a 

chemical balance of carbon (or oxygen) between the fuel, inlet air, and 

raw exhaust to calculate raw exhaust flow as described in Sec.  

1065.650, as follows:

    (1) Use the actual value of calculated raw exhaust flow rate in the 

following cases:

    (i) For multiplying raw exhaust flow rate with continuously sampled 

concentrations.

    (ii) For multiplying total raw exhaust flow with batch-sampled 

concentrations.

    (2) In the following cases, you may use a fuel flow meter signal 

that does



[[Page 705]]



not give the actual value of raw exhaust, as long as it is linearly 

proportional to the exhaust molar flow rate's actual calculated value:

    (i) For feedback control of a proportional sampling system, such as 

a partial-flow dilution system.

    (ii) For multiplying with continuously sampled gas concentrations, 

if the same signal is used in a chemical-balance calculation to 

determine work from brake-specific fuel consumption and fuel consumed.

    (b) Component requirements. We recommend that you use a fuel flow 

meter that meets the specifications in Table 1 of Sec.  1065.205. We 

recommend a fuel flow meter that measures mass directly, such as one 

that relies on gravimetric or inertial measurement principles. This may 

involve using a meter with one or more scales for weighing fuel or using 

a Coriolis meter. Note that your overall system for measuring fuel flow 

must meet the linearity verification in Sec.  1065.307 and the 

calibration and verifications in Sec.  1065.320.

    (c) Recirculating fuel. In any fuel-flow measurement, account for 

any fuel that bypasses the engine or returns from the engine to the fuel 

storage tank.

    (d) Flow conditioning. For any type of fuel flow meter, condition 

the flow as needed to prevent wakes, eddies, circulating flows, or flow 

pulsations from affecting the accuracy or repeatability of the meter. 

You may accomplish this by using a sufficient length of straight tubing 

(such as a length equal to at least 10 pipe diameters) or by using 

specially designed tubing bends, straightening fins, or pneumatic 

pulsation dampeners to establish a steady and predictable velocity 

profile upstream of the meter.