Shaft seals, a vital part of refrigeration systems, are both expensive to replace and costly to stock in case of seal failure. Bonar Engineering, Inc. is proud to announce the opening of its seal research lab facility. The lab incorporates factory training, state of the art equipment, failure analysis, quality control testing, a file to document all rebuilds and causes of seal failure, as well as parts for emergency seal repair. This service is provided by Bonar Engineering to help keep operating costs down while providing reliable seal designs and reconditioned replacements.
With today’s economically cautious times, many companies in various industries are trying to reduce operating costs. In the industrial refrigeration industry, very few parts can be bought in the aftermarket. One, however, that has been infiltrating refrigeration has been mechanical shaft seals. Shaft seals are expensive due to the engineering and special materials used for specific applications. Original equipment manufacturers go to great lengths in the research, engineering, and testing of the materials and designs of the shaft seals. Aftermarket seals may look like originals. Visually, correct materials cannot be identified.
There are hundreds of combinations of materials that can be used in seal designs. Carbon is black, however it does have many grades and bonding agents. Most O-rings are black, but which material is specified for your particular application? Protect your personnel and equipment –use only OEM seals and certified rebuilders.
Rotating shaft seals used for ammonia closed refrigeration cycles are becoming increasingly important with ammonia’s expanding use as a refrigerant. Shaft seals, whether they contain gas or liquid, are becoming increasingly reliable as material technology improves. Engineering, research, and many years of experience have developed sealing systems which offer a high degree of reliability. With proper materials, proper pump application and installation, new and rebuilt seals can help maintain good working environments without excessive risk from the pungent odors or hazards of ammonia refrigerant.
Many questions are asked pertaining to seals. Some of the most frequent are answered in the following discussions.
Question #1: When is carbon carbon?
Question #2: What is a black “O” ring?
Question #3: Why are mechanical shaft seals expensive?
Answer #1: There are many different grades of carbon and bonding agents (some specifically for ammonia applications). To make carbon “blister resistant”, the bonding agent needs to be compatible with the fluids it is sealing. Quite obviously, carbon best suited for sealing ammonia may not be as suitable for oils or vice versa. The placement of the carbon and flush points in the seal assembly is equally important to its ability to withstand refrigerant flashing when it is used for cooling the seal cavity.
Answer #2: Most “O” rings used in seal configurations are black in color, however, like carbon, many different materials are used, depending on application. The most frequently used material for ammonia is Neoprene. Some ammonia pumps using “double” seal configurations have oil on one side and ammonia on the other. The same fluid and fluid temperatures provide a more consistent condition for “O” rings.
Answer #3: The cost of a mechanical shaft seal reflects material and production costs, as well as many hours of engineering and testing. Manufacturers of equipment in the ammonia refrigeration industry go to great lengths testing and re-designing shaft seals to minimize seal failures. Seals may appear the same by visual inspection, however, they can be completely different in the materials and how they are applied.
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