What safety procedure should be followed when starting a larger reciprocating machine without unloaders?

When starting a larger reciprocating machine without unloaders, the recommended safety procedure is to open the suction valve and the discharge bypass. This approach allows the machine to start while minimizing the load on the compressor, preventing potential damage or mechanical failure.

Opening the suction valve enables the machine to draw in refrigerant or gas, ensuring that it has the necessary flow to operate efficiently. Additionally, opening the discharge bypass allows the compressed gas to return to the suction side, effectively reducing back pressure. This reduces the mechanical strain on the machine during startup, as reciprocating compressors are sensitive to sudden increases in load and pressure.

By following this procedure, operators can ensure a smoother and safer startup process, avoiding excessive stresses that could lead to equipment malfunction, reduced efficiency, or even damage to the machine.