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Calibration of the Zahm & Nagel Dial Thermometers

The dial thermometer can be easily re-calibrated by the following method:

  1. Remove the Thermometer from the instrument and insert the stem into a plastic vessel of crushed ice and distilled water. Make sure that the stem is covered by this mixture for a distance of 2.0 inches from the tip of the stem.
  2. Place a laboratory thermometer in the ice/water bath to assure that the temperature is 32° F / 0° C.
  3. Place an adjustable wrench on the hex nut located at the bottom of the dial and turn the nut in the direction needed for re-calibration.
  4. Since the thermometers are 1% accurate in the entire range, setting the needle pointer to 32° F / 0° C. will assure accuracy in the entire temperature range.
  5. Remove the thermometer from the bath and insert into the instrument. Be sure to place “O” ring lubricant on the thermometer stem. This will lubricate the “O” ring. Tighten the thermo-adapter nut just enough to allow movement of the thermometer. Now test for leaks by pressurizing the instrument and immersing under water. Look for bubbles around the thermo-adapter.

For more, please view our video detailing Zahm Thermometer Calibration below:

Recommendation for Care and Calibration of Instrument Gauges

Gauges should be re-calibrated on a regular basis. This is easily done by removing the face cover and with the use of a mercury column gauge tester, dead weight tester or known accurate pressure supply, simply adjust the recal screw with a screwdriver to the desired pressure reading. In the case of the slotted adjustable needle pointer, the screwdriver is inserted into the slot, held in that position and the needle turned (not the screwdriver) to the desired corrected pressure. Care should be used when turning the thin needle pointers so as not to bend or break them off the stud post. A gauge is most accurate in its mid-range scale and the user should choose a gauge that will cover his tests in this range.

CLEANING: It is suggested that the cover/case be removed from the gauge, and the internals flushed with warm water. Be careful not to damage the hairspring when cleaning the internals. Warm water may also be introduced into the Bourbon Tube through the bottom lower male port.

Gauges may be returned to Zahm & Nagel Co. for repair if the customer does not have re-calibration facilities. Gauges will be inspected and the customer quoted cost to repair.

For more, please view our video detailing Zahm Gauge Calibration below:

Maintenance of Zahm Ceramic Stones

When a tank is emptied, stones should be removed as soon as possible so as to prevent beer from drying on the stones. Such stones should be kept wet in a bucket of water until they are flushed out. The flushing rack built for this purpose is connected to cold water and gas or clean air lines, and may also be provided with hot water or steam to advantage.

The stones are placed in the rack and cold water allowed to flow through until the stone is well flushed. The water is then turned off and air or gas pressure of 7 ½ lbs established and then slowly raised. If the stones are in free porous condition, gas bubbles should come through at a pressure from 7 ½ to 8 lbs. If a higher pressure is required, it indicates that some of the pores are clogged, and a more vigorous cleaning is necessary. Stones that are free flowing may be blown out with water or gas and stored in a dry place until required for further use.

Stones that are definitely plugged should be flushed and blown and then thoroughly dried after which they should be soaked in RBS-35 solution, following the instructions on the container. RBS-35 is available from the Pierce Chemical Co. (1-800-8-PIERCE) or your chemical products supplier.

From three to twenty-four hours is generally sufficient to remove the plugging material. After removal, the stones are very thoroughly flushed with water and then tested as outlined above. In exceptional cases, it may be necessary to repeat the treatment after again thoroughly drying the stones.

Cleaning Information 316 L Porous Material

DO NOT mechanically clean porous metal elements. Wire brushing, scraping, sand or glass bead blasting can smear the pores and close off the porous media.

Chemical cleaning follows a logical sequence. First determine what contaminants present in the filter. Next, determine the chemical agents that will dissolve these contaminants (without dissolving or attacking the porous metal). The chemical agents compatible with 316L stainless steel porous media could be, but are not limited to:

Water at any temperature15% nitric acid up to 150° F
20% caustic up to 212° FAlcohol
Acetic acidAcetone
AmmoniaOrganic solvents
Methylene chlorideDetergents
SolventsIndustrial cleaners such as Oakite 31 or Sonicor #103 (to remove all grease or oil)

Soak the elements in the chemical agent as required, flush with clean filtered water or other compatible fluid, blow out with clean air or steam. Two chemical agents may be required, such as 15% nitric acid to remove iron oxide and 20% caustic to remove aluminum particulate, with a water flush between soaks.

To remove inert or insoluble solids from porous metal elements ultra-sonic cleaning is an effective process. The fluid medium usually contains a detergent for maximum efficiency of removal. It is recommended that ultra-sonic transducers provide at least 60 watts per gallon of fluid in the ultra-sonic bath. Cleaning may require from 10 to 60 minutes. Optimum results are obtained when cleaning solution is flowed through the element in reverse direction during ultra-sonic cleaning.

For elements used for gas solids service it is necessary to bake the elements in an oven at 300° F to 400° F after cleaning to assure that all moisture is removed from the element.