Foster BL75FS, 3/4" Straight-Thru Coupler x 3/4" Female NPT, FST Series, Ball Lock, Brass

Product Details

Maximum flow with no restriction, for air and fluid lines where shut-off is handled elsewhere. The Foster BL75FS is a brass 3/4" straight-thru coupler in the FST Series, with a female NPT end and the Standard Industrial Interchange profile. Full-flow bore, no valve in either half, rated to 1700 PSIG. Ball-lock sleeve. Interchanges with Breco ST and other Standard Industrial straight-thru halves of the same body size.

Why this coupler

• Full flow, no valve — the bore matches nominal pipe ID, so there is no pressure drop across the coupling.
• Standard Industrial Interchange — the most widely used profile; couples with any same-size straight-thru half.
• Ball-lock sleeve — align the ball with the slot and rotate to lock against accidental disconnect.
• Brass body — rated to 1700 PSIG with a 4:1 safety factor per ANSI/B93.2.

Frequently asked questions

What does straight-thru mean?
Neither the coupler nor the plug contains a valve. The bore runs straight through at full pipe diameter, giving maximum flow with no pressure drop. The trade-off is that the line does not self-seal when you disconnect it.

Will the line seal when I disconnect?
No. FST straight-thru halves have no valve, so both sides stay open. Shut off and relieve pressure upstream before disconnecting, or use a valved series instead.

What plug does it take?
Any 3/4" straight-thru plug on the Standard Industrial Interchange. The matching part is 75FPB.

Why buy from hpcouplers: Foster quality, responsive US-based support, accurate specs, fast shipping.

FST Series (Straight-Thru) — Complete Series Chart

Every part in the series, grouped by body size. Each coupler row shows its exact matching plug — click any part number to open that product. Brass and stainless couplers take their matching-material plug.