Compressors and pumps will transmit vibration to their connecting pipework. Mounting methods will be recommended by manufacturers and should be used. Where vibration eliminators (Figure 11.2) are inserted in suction and discharge lines, they should be in the same plane as the compressor shaft, i. e. horizontal for semi-hermetic and open reciprocating types and vertical for all vertical scrolls.
Figure 11.2 Vibration eliminator (Henry)
Water and brine pumps may be isolated with flexible connectors. For small-bore pipes, these can be ordinary reinforced rubber hose, suitably fastened at each end. For larger pipes, corrugated or bellows connectors of various types can be obtained. In all cases, the main pipe must be securely fixed close to the connector, so that the latter absorbs all the vibration. Flexible connectors for the refrigerant usually take the form of corrugated metal hose, wrapped and braided. They should be placed as close to the compressor as possible.
A great deal of vibration can be absorbed by ordinary piping up to 50 mm or 65 mm nominal bore, providing it is long enough and free to move with the compressor. Three pieces, mutually at right angles and each 20 diameters long, will suffice. At the end of these vibration-absorbing lengths, the pipe must be securely fixed.
In all instances of antivibration mounting of machinery, care must be taken to ensure that other connections — water, electrical, etc. — also have enough flexibility not to transmit vibration.
Posted in Refrigeration and Air Conditioning