Is OS&Y always required?

Follow the fire graph and AHJ — many above-ground control valves call OS&Y.

Do I need a tamper switch?

Often yes on supervised valves — state it on the RFQ.

Fire protection specs often require OS&Y for visible stem position, while NRS is used where space or bury service applies.

Topic	OS&Y	NRS
Stem	Rising — position visible	Non-rising
Typical fire use	Indoor indicating control valves	Buried / space-limited as allowed
Space	Needs stem clearance	Compact height
Supervision	Tamper switch common	Tamper switch common
RFQ cue	UL/FM OS&Y + size	UL/FM NRS + ends

Write UL and/or FM, OS&Y or NRS, size, ends (flanged/grooved), and tamper switch clearly.