433A Pumps and Compressors 6

Question 1

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

Accepted Answer

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

Answer

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.

Question 2

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

Accepted Answer

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

Answer

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.

Question 3

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

Accepted 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

Answer

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.

Question 4

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

Accepted Answer

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

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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.

Red Seal Millwright 433A Practice Test

Red Seal Millwright 433A Practice Test

433A Pumps and Compressors 6