Which valve type is commonly associated with leakage due to clearance between the spool and bore, potentially enlarging the bore when contaminated?

Which valve type is commonly associated with leakage due to clearance between the spool and bore, potentially enlarging the bore when contaminated?

• A. Slide valve
• B. Ball valve
• C. Globe valve
• D. Needle valve

Answer: (A)

Leaking along a spool-to-bore clearance is a hallmark of sliding-spool valves. In these valves, the moving spool slides inside a fixed bore and relies on very tight tolerances to seal off flow paths. When contaminants get in, abrasive particles can score and wear the bore and the spool, enlarging the clearance. That bigger gap lets fluid bypass the intended paths, causing leakage and, if wear is significant, further enlarging the bore and worsening leakage over time. Ball, globe, and needle valves seal differently: their leakage is mainly through seats or seals around a ball, disk, or needle, not through a gap between a sliding element and its bore. So the described issue—leakage due to clearance between the spool and bore with contamination-caused bore enlargement—points to the slide (spool) valve.

Leaking along a spool-to-bore clearance is a hallmark of sliding-spool valves. In these valves, the moving spool slides inside a fixed bore and relies on very tight tolerances to seal off flow paths. When contaminants get in, abrasive particles can score and wear the bore and the spool, enlarging the clearance. That bigger gap lets fluid bypass the intended paths, causing leakage and, if wear is significant, further enlarging the bore and worsening leakage over time.

Ball, globe, and needle valves seal differently: their leakage is mainly through seats or seals around a ball, disk, or needle, not through a gap between a sliding element and its bore. So the described issue—leakage due to clearance between the spool and bore with contamination-caused bore enlargement—points to the slide (spool) valve.