Ball Valves

illustration ball valve


Forespar® MF 850 series of Ball Valves are precision molded in high strength glass-reinforced Marelon®. Great strength, light weight, easy installation and maintenance as well as freedom from corrosion and electrolysis creates the ideal valve for controlling inlet and outlet water flow above and below the waterline.

Stringent testing makes MF850 valves meet or exceed industry standards, allowing you to rely on our high quality. For instance, our engineers opened and closed a ¾” (19.05mm) valves 11,000 times, then submerged it connected to an air line pressurized to 40 p.s.i.. The result was an absolutely leak free valve with no evidence of wear on internal seals.

All valves sold throughout the U.S.A. have standard NPSM type threads. If specified, B.S.P. threads are available on valves sold outside of North America.

And, the operating temperature range of Marelon® is -40° F to +176°   (-40°c to +80°c), making the valves reliable in every climate and season.  


Zero corrosion, zero electrolysis, light weight, strong marine grade


The temperature range of Marelon is: -40F to +176F or -40C to +80C


All Marelon products are carbon fiber reinforced


All 93 series valves are U.L. approved and ISO certified


Port Sizes


93 Series

1/2" (12.7mm) = .462" (11.73mm)

3/4" (19.05mm) = .52" (13.2mm)

1" (25.4mm) = .79" (20.06mm)

1-1/4" (31.75mm) = 1.05" (26.67mm)

1-1/2" (38.1mm) = 1.25" (31.75mm)

2" (50.8mm) = 1.54" (39.11mm)


849 & 850 Series

1/2" = 5/8"

3/4" = 5/8"

1" = 15/16"

1-1/4" = 15/16"

1-1/2" = 1-5/16"

2" = 1-13/16"





Part No




850 Inline Ball Valve 1/2" NPSM



850 Inline Ball Valve 3/4" NPSM



850 Inline Ball Valve 1" NPSM



850 Inline Ball Valve 1-1/4" NPSM



850 Inline Ball Valve 1-1/2" NPSM



850 Inline Ball Valve 2" NPSM



The 93 Series valves are designed and engineered for builders, boat yards and owners who require the benefits of the high-strength glass reinforced Marelon® Integrated Plumbing System with “standard” female threads. These valves will work on and integrate with Marelon®, bronze or stainless steel NPT threaded thru-hulls and are available with female/female (Forespar Part# 933332-8), straight tailpipe (933342-8) or 90° elbows (933352-8) already attached. All “93” series valves are full port (the Inside Diameter of the ball is the same as the I.D of the barb).

93 Series Chart - OEM Sales Only

ball valve threaded
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