The Frazier Differential Pressure Instruments are built into a table and are shipped completely assembled and calibrated.
1. Uncrate the instrument by carefully removing the wood crate and inner paper cover. Keep in mind that the instrument contains delicate exposed glass tubes.
2. Lift the table containing the instrument off of the crate base and place it where it will be used.
3. Verify that the variable transformer indicates "0" and switch is in the off position and plug the instrument into an appropriate electrical outlet. Make sure that the transformer reads "0" before you start any procedure. This is very important.
4. Level the instrument by means of the adjustable screws in each table leg so that the Bubble Level mounted on the manometer (below the slant tube) is correct. The Bubble Level itself should never be moved or adjusted or the instrument will become out of calibration. The built in bubble level is used solely to indicate the correct slant of the inclined manometer and is set during manufacture. Again, this level should never be adjusted. Adjustment of the level itself will destroy the calibration of the instrument. It must then be returned to the factory for complete recalibration.
5. Since your instrument is a High Pressure instrument both manometers reservoir cans are located on the table. Add the proper Red Oil - specific gravity 0.827 (included in the shipment) to the two manometers until they read zero. Be sure not to overfill above the zero mark. A slight up or down movement of the scale to bring the zero line of the scale to the level of the oil in the glass tube is permissible only for the right hand manometer. The left hand manometer scales should never be adjusted. However adjust the oil level so that the top level of the oil is at least 1/4 inch below the top of the reservoir can. Note that the left hand filler cap is vented and the right hand one is not vented. Do not switch them. Make sure that there is not an oil bubble in the opening of the left reservoir.
6. Clamp the 4 mm standard test plate onto the 2 3/4 inch diameter test opening on the top of the table (where the samples are normally tested) and screw the 4 mm nozzle into the chamber below the table. Note: The Test Plate is not a calibration plate and it cannot be used to calibrate your instrument. The door should then be latched closed firmly, but it need not be air tight.
The transformer switch should then be placed in the "on" position and its knob should be slowly rotated to increase the speed of the blower. Watch the oil in the inclined (left hand) manometer being pulled up. Adjust the speed of the motor until the inclined manometer reads 0.5" of water (The instrument reads in inches of water even though oil is in the manometer.)
Observe the position of the red oil in the vertical (right hand) manometer. This reading of the right hand vertical manometer should then be noted. (Be sure not to run the oil over the top of the manometer.) The corresponding air flow in terms of cubic feet of air flow should be taken from the 4 mm column of the proper calibration chart. Use calibration chart w/ the same serial number as the nozzle used. For example, if the elevation of the red oil is at the 10" line then the air flow is (read from calibration chart) cubic feet of air per square foot of sample material. Most likely the reading will not be a whole inch such as given in the calibration chart. Air flow at the 1/10 of an inch can be computed from the calibration chart by doing a straight interpolation between the whole inches given. For example the air flow for 10.5 should be assumed to be halfway between the reading for the 10" and the 11" on the calibration chart. The value of your specific test plate given on the calibration chart is (read from test plate card) C.F.M. so the oil should be approximately on the (interpolated from calibration chart) line.
If you obtain substantially the same reading as the actual calibration shown on the card that was included with the Test Plate, you can be confident that the instrument is working correctly. This reading should be repeatable for years. If you obtain a significant variation either the calibration of the test plate or nozzle (or both) has changed or the instrument itself is not in good operating order. The most common reason why the instrument would not be operating properly is that oil has been drawn into the system through operator error. Other special test plates are available to check the calibration of each of the other nozzles. See the "Test Plates and Calibration" FAQ.
7. Samples are tested by the same procedure as per 6 above. (A test plate represents an unchanging sample). However the operator should be alert, especially when testing unknown samples, not to increase the speed of the blower to the extent that one or the other of the manometers has oil pulled into the system. Please note that oil in the two manometers does not move at the same speed. This movement varies with the sample tested. Extreme caution should be taken. If oil is pulled into the system (e.g.. the oil disappearing over the top of the glass tubes or beyond the highest available reading) the instrument will not read correctly until the oil is completely cleaned out. Please see the "Maintenance Instructions" Since oil in the system is always due to operator error and it is the most common problem, please note that it is not covered by the warranty.
8. The size of the nozzle you use in testing depends on the porosity of the material under test. The greater the porosity the greater the opening of the nozzle. But at all times the nozzle should be small enough that the red oil of the vertical manometer reaches at least the 3" line. (The machine is not as accurate below the 3" line.)
9. May we add that the Test Plate (See "Test Plates and Calibration") is supplied for detecting malfunctions of the machine, caused by air leakage through the filler plug of the right hand oil reservoir, or oil in the system (accidental overflow of the red oil into the copper connecting tubes) etc. In this case a thorough cleaning of these tubes with a cleaning fluid, such as Acetone becomes necessary (See "Maintenance Instructions") The Test Plate cannot be used to calibrate your instrument, although it can be used to verify the calibration of the instrument.
We recommend that Test Plates be recalibrated yearly by Frazier Company due to possible changes through handling over time.
Yearly calibration is also a partial requirement for ISO certification.