ASTM D5275 Test Method for Fuel Injector Shear Stability Test (FISST) for Polymer Containing Fluids
7. Precautions
7.1 During operation, the line between the pump and the nozzle holder is under high pressure. The safety shield should be in place when the apparatus is running. Stop the apparatus before tightening any fitting that is not properly sealed.

7.2 During operation and during the setting of the valve opening pressure, the fluid is discharged from the nozzle at high velocity and can inflict a serious wound if it strikes a part of the human body. Therefore, secure the nozzle assembly in position before the test apparatus is started. Similarly, take care to shield the operator from the nozzle discharge during the pressure-setting step.

8. Sampling
8.1 The test fluid shall be at room temperature, uniform in appearance and free of any visible insoluble material prior to placing in the test equipment.

8.2 After the test fluid has completed its twentieth cycle through the apparatus, drain it into a bottle for transfer to the kinematic viscosity measurement.

9. Calibration
9.1 Set the valve opening pressure of the diesel injector nozzle assembly to 20.7 MPa +/- 0.35 MPa (3000 psi +/- 50 psi) by means of a hand-actuated pump and diesel fuel.

9.2 Set the delivery rate of the pump to 534 cm3 +/- 12 cm3/min by the procedure described in Annex A1.

9.3 Verify the shearing severity of the apparatus by running the standard test procedure, described in 9.3.1, with reference oil. Make this check every twentieth run when the apparatus is used frequently. Make this check before any other samples are tested if the apparatus has been idle for a week or more. The kinematic viscosity at 100 °C for the sheared reference oil is to be within the limits prescribed for the specific batch of the reference oil in use. For oil TL-11074, the limits are 9.64 mm2 and 9.94 mm2/s at 100 °C.
9.3.1 If the viscosity of the sheared oil does not fall within the above limits, make another shear test of the reference oil by the standard procedure. If the viscosity of the sheared oil still does not fall within the limits, take steps to correct the rating level of the test. Either mechanical difficulty or test technique is at fault.