Pumps and Compressors Flashcards

What is the function of the anti-surge valve on a centrifugal compressor?

Answer: To maintain minimum flow through the compressor by recirculating gas, preventing the compressor from entering the unstable surge zone

The anti-surge valve automatically opens to recirculate discharge gas back to the suction when flow approaches the surge limit, maintaining minimum flow through the compressor and preventing the destructive flow reversal associated with surge.

What is a peristaltic (hose) pump and what is its primary advantage?

Answer: A pump that compresses a flexible tube with rollers to push fluid, ensuring zero contamination since fluid only contacts the tube

A peristaltic pump uses rollers compressing a flexible tube to push fluid forward, like squeezing toothpaste from a tube. Since the fluid only contacts the tube interior, there is zero contamination from pump components, making it ideal for sterile, corrosive, or sensitive fluids.

What is the correct procedure for packing a pump stuffing box?

Answer: Install individual pre-cut packing rings one at a time with joints staggered, seat each ring before adding the next, and position the lantern ring correctly

Packing rings must be individually cut to proper length, installed one at a time with butt joints staggered (typically 90 or 120 degrees apart), each ring seated firmly before the next is added, and the lantern ring properly positioned at the flush/seal water port.

What is the effect of running a compressor with a dirty inlet air filter?

Answer: Reduced inlet pressure causes higher compression ratio, increased discharge temperature, reduced capacity, and higher energy consumption

A dirty inlet filter creates a restriction that reduces inlet pressure. The compressor must work harder (higher compression ratio) to achieve the same discharge pressure, resulting in higher temperatures, reduced air delivery, and increased energy consumption.

What is the purpose of a pump's baseplate drain?

Answer: To collect and safely contain any fluid that leaks from the pump seals or packing, preventing environmental contamination

The baseplate drain collects any fluid that escapes from the pump packing or mechanical seal and directs it to a safe containment point, preventing environmental contamination and providing a visible indication of seal condition.

Why is it important to follow the manufacturer's torque sequence when assembling a pump casing?

Answer: To ensure even clamping force, prevent gasket distortion, and avoid warping the casing that could cause misalignment or leaks

Following the manufacturer's torque sequence (typically a star/cross pattern with multiple passes) ensures even bolt loading, prevents gasket crushing or displacement, avoids casing distortion that could affect internal clearances, and ensures a leak-free assembly.