Set-Up for Operating:

The pressure gauge has been calibrated to +/- 1/4 pound psi at the factory prior to shipment of the instrument. If, after a period of use, there is a question of gauge accuracy the following checks should be performed on the gauge:

The gauge should be checked and calibrated using any of the following instruments:

• A Zahm & Nagel Series #8000 Gauge Tester
• A Dead Weight Tester
• A calibrated Test Gauge Digital

The most accurate range of the gauge is the mid-range and the needle should be set in this area. To re-set the needle, remove the face cover and insert a small screwdriver into the slotted brass screw located at the 5 o'clock position of the gauge. Turn the screw-driver clockwise or counterclockwise to match the pressure established on one of the above testing devices. A "Zero Zone" is located on the gauge and the needle may rest in any area of this zone and still be in calibration. Do not attempt to calibrate the gauge in this zone. Gauges that are out of calibration may be returned to Zahm & Nagel for re-calibration.

The thermometer liquid column may become separated due to rough handling. The column may be re-joined by following the instruction sheet on "Separated Columns" that is shipped with this instrument. These instruction sheets are also available from Zahm & Nagel Co. upon request. Replacement thermometers are also available from Zahm & Nagel Co.

WARNING: OPERATOR MUST WEAR EYE PROTECTION WHILE OPERATING THIS INSTRUMENT.

OPERATING:

Before using the Volume Meter, rinse the inside with cold water. This will help prevent gas bubbles from adhering to the internal surfaces of the Volume Meter when it is being filled.

1. Close the inlet valve (2035) and the bleeder valve (3003).
2. Open the overflow valve (2002) and pump the aspirator bulb (1042) until a pressure of 10 psi is indicated on the gauge (2013).
3. Close the overflow valve (2002) and allow the instrument to stand for several minutes. If the gauge shows any pressure drop, a leak is indicated and may be detected by applying a soapy water solution to the various fittings and the condition corrected.
4. Attach the Volume Meter to the trycock on the tank by turning the U-bolt nut (2045) on the clamping device (2037) to its most open position (out) and place the Volume Meter over the boss of the trycock.
5. Spin the U-bolt nut closed to seal the Volume Meter tightly to the trycock.
6. Make sure the bleeder valve on the pressure gauge is closed and then open both the inlet (2035) and the overflow (2002) valves on the Volume Meter.
7. Pump counter-pressure into the Volume Meter with the aspirator bulb. The counter-pressure should be equal or slightly less than the pressure of the tank, plus the hydrostatic head pressure of the beer above the trycock. For example: if the tank pressure is 8 psi and the beer level is 6 feet above the trycock or approximately 3 psi pressure, 11psi counter-pressure should be established in the Volume Meter.
8. Close the overflow valve (2002) and remove the aspirator bulb (1042) from the Volume Meter.
9. Open the trycock on the beer tank to allow beer to flow into the Volume Meter. However, due to the counter-pressure established in the Volume Meter, the beer will be prevented from flowing into the instrument. In order to establish flow, slightly open the overflow valve (2002) and allow the pressure to drop slowly in the Volume Meter. To avoid too rapid a release of pressure, which would have a disturbing effect on the beer flowing into the Volume Meter, let the pressure gauge act as a guide. A pressure drop of ½ to I psi will allow the Volume Meter to fill properly. When the filling operation is properly performed, the beer will quietly fill the Volume Meter with a minimum of released gas. It is advisable to have the Volume Meter cooling in the cellar a short time before making the test. The beer is now allowed to completely fill the overflow tube (2001). A small amount of beer is allowed to escape to remove free gas bubbles.
10. Close the overflow valve (2002) and also the inlet valve (2035).
11. Close the trycock on the beer tank and remove the Volume Meter by releasing the U-bolt on the clamping device (2037).
12. Remove a small definite amount of beer from the Volume Meter to allow proper agitation and to make possible the equilibrium condition between free and dissolved gas upon which the operation of the instrument is based. To remove the beer, open the bleeder valve (3003) and allow the beer to flow out of the bleeder valve until it reaches the indicated beer level line on the sight glass (2006). It is best to release the beer in three or more portions, and after each release hold the Volume Meter vertically by the handles and rotate the Volume Meter in a circle while keeping the sight glass (2006) at a fixed point. This motion will bring the gas that will be released when each portion of the beer is removed up into the sight glass so that the liquid level can be more accurately adjusted to the beer level line. A level of 1/16" above or below the line will cause only a minor error and, unless most exact results are desired, such an adjustment will be sufficiently accurate. If beers of low CO2 content are to be tested, it may be necessary to warm the sample to obtain sufficient pressure to bleed off the required amount.
13. Now after the beer level has been adjusted to the line described, hold the Volume Meter by the two handles in a horizontal position and vigorously agitate the instrument. This agitation causes the rapid establishment of equilibrium between the free and dissolve gas. Under conditions of equilibrium the number of volumes of gas in a given beer will be in constant relationship to the temperature and pressure conditions. That is to say, a beer having a fixed volume of CO2 gas in solution will show the same pressure at a given temperature and conversely, the same temperature at a given pressure. When the temperature and pressure remain constant these indications are referred to the chart from which the number of volumes of CO2 gas at zero degrees C., 760mm pressure per volume of beer is stated. When making the pressure reading, always hold the Volume Meter in a vertical position so as to obtain accurate indications. After one set of readings has been taken, agitate the instrument again and check the temperature and pressure indicated. There should be no material difference if the temperature has remained constant.
    
    The chart furnished with the Volume Meter was compiled after extensive laboratory research. Samples were taken from a tank containing carbonated beer at equilibrium with undissolved gas. One set of these samples was tested with the Volume Meter using the method previously described while the other set was analyzed by exact chemical methods. The result of these analyses were plotted against the temperatures and pressures as indicated by the Volume Meter in testing each duplicate sample. Hence, the chart gives the number of volumes of CO2 gas dissolved per volume of beer as contained in the tank from which the sample was taken and does not indicate the number of volumes of gas dissolved in the sample contained in the Volume Meter. This is due to having liberated 3% of the dissolved gas to replace the beer in the space above the beer level line in the Volume Meter. When the Volume Meter is used at high altitudes, or when the barometer is low, or if very exact results are desired, the pressure gauge reading should be corrected before reference to the chart is made. Deduct 0.2 psi for every 10mm mercury indicated by the barometer below the standard condition of 760mm mercury. If the percentage of weight of CO2 gas is desired, the following formula may be used:
    
    

    Volume of CO2 x O.197 Specific Gravity of Beer

    = % CO2 weight

    
    NOTE: The Volume Meter chart gives solubility of CO2 gas in average beer, and will be found to give lower reading than charts based on solubility in water.