20.B.07 Governors.
- A speed governor, independent of the unloaders, must be installed on all air compressors except those driven by electrical induction or electrical synchronized motors.
- If the air compressor is engine or turbine driven, an auxiliary control to the governor must be installed to prevent racing when the unloader operates.
20.B.08 Every air compressor must automatically stop its air-compressing operation before the discharge pressure exceeds the maximum working pressure allowable on the weakest portion of the system.
- If this automatic mechanism is electrically operated, the actuating device must be so designed and constructed that the electrical contact or contacts cannot lock or fuse in a position that will cause the compressor to continue its operation.
- An air bypass and alarm may be used as an alternative.
20.B.09 Provisions must be made to exclude flammable materials and toxic gases, vapors, or dusts from the compressor and compressor intake and to prevent steam, water, or waste being blown or drawn into a compressor intake.
20.B.10 No valve must be installed in the air intake pipe to an air compressor with an atmospheric intake.
20.B.11 The air discharge piping from the compressor to the air receiver must be at least as large as the discharge opening on the air compressor.
20.B.12 A stop valve must be installed between the air receiver and each piece of stationary utilization equipment at a point convenient to the operator, and a stop valve must be installed at each outlet to which an air hose may be attached.
20.B.13 If a stop valve is installed between the compressor and the receiver, spring-loaded safety valves must be installed between the air compressor and the stop valve.
- The capacity of safety valves must be sufficient to limit pressure in the air discharge piping to 10% above the working pressure of the piping.
- Stop valves should be of the gate type. If a globe valve is used, it must be installed so that the pressure is under the seat and that the valve will not trap condensation.
20.B.14 Provisions must be made in compressed air and gas systems for expansion and contraction and to counteract pulsation and vibration.
20.B.15 Piping must be equipped with traps or other means for removing liquid from the lines.
20.B.16 Air discharge piping must be installed to eliminate possible oil pockets.
20.B.17 Installation and location of air receivers.
- Air receivers must be installed so that all drains, hand holes, and manholes are accessible.
- Air receivers should be supported with sufficient clearance to permit a complete external inspection and to avoid corrosion of external surfaces.
- Air receivers must not be buried underground or located in inaccessible places.
- The receiver should be located to keep the discharge pipe as short as possible.
- The receiver should be located in a cool place to facilitate condensation of moisture and oil vapors.
20.B.18 A drain valve must be installed at the lowest point of every air receiver for the removal of accumulated oil and water.
20.B.19 Automatic traps may be installed in addition to drain valves.
20.B.20 The drain valve on the air receiver must be opened and the receiver drained often enough to prevent the accumulation of excessive liquid in the receiver.
20.B.21 No tool change or repair work must be done until the stop valve in the air line supplying the equipment is closed.
20.B.22 Soapy water or any suitable non-toxic, non-flammable solution may be used for cleaning the system.
20.B.23 Hose and hose connections used for connecting compressed air to utilization equipment must be designed for the pressure and service to which they are subjected and utilized in accordance with the manufacturer's specifications.
Knowledge Check Choose the best answer for the question.
20-4. When must the air compressor automatically stop its air-compressing operation?
You forgot to answer the question!