Forespar Marelon Plumbing — Catalogue

What the Catalogue Covers

The PDF is laid out in two-page spreads; page numbers above are the ones printed on the catalogue pages. The extra download is a 4-page Marelon summary with the most popular Pro Series, 850/849 and thru-hull part numbers.

Building a Pro Series Part Number

• Every Pro Series valve number starts with 93, followed by Base #, Body #, Top #, Size # and optional modifiers. Example: 931155 = base 1, body 1, top 5, size 5.
• Seacock style Pro Series valves come with their own Marelon buttress-thread thru-hull and must be used with it; with the "N" modifier they get an NPSM threaded base for most other thru-hulls.

Base (third digit)

• 1 – Flanged seacock base with a mushroom head buttress threaded thru-hull
• 2 – Flanged seacock base with a flush head buttress threaded thru-hull
• 3 – Female NPSM threaded base
• 4 – Straight barbed tailpipe
• 5 – 90 degree elbow barbed tailpipe
• 6 – Flanged seacock base with a screened flush head buttress threaded thru-hull
• 7 – Flanged seacock base with a screened mushroom head buttress threaded thru-hull

Body (fourth digit)

• 1 – Straight flow, single port with a thru-hull plug for use with the buttress thru-hulls
• 2 – Double port "Y" valve, body barb opposite the handle, with a thru-hull plug
• 3 – Straight flow, single port with no thru-hull plug; only a flush cap on the handle
• 4 – Double port "Y" valve, body barb opposite the handle, with a flush cap on the handle
• 5 – Double port "Dual Drain", body barb opposite the handle and a thru-hull plug
• 6 – Double port "Dual Drain", body barb opposite the handle and flush cap handle

Top (fifth digit)

• 3 – Female threads
• 4 – Straight hose barb tailpipe
• 5 – Low profile 90 degree elbow hose barb
• 6 – Blank top only (very few configurations, body 5 & 6 only)
• 7 – Female garden hose fitting (engine flush-out valves only, body #2 & 4; not shown)

Base options added in this catalogue

• 8 – Black thru-hull (standard is white)
• 9 – Extra long thru-hull (5-3/4" long)

Modifiers (suffix)

• N – NPSM straight threaded base (no thru-hull or thru-hull plug)
• B – BSP threaded base (1" to 2"), no thru-hull or handle plug
• C – Chromed mushroom head buttress thread thru-hull
• L / R – Top elbow faces left / right (looking at the top of the valve, handle facing down)
• E – For use with an ROV electric motor (OEM only)
• V – Anti-venturi style thru-hull (no thru-hull plug)
• K – Handle lock-off plate for USCG requirements, standard padlocks (1" & 2" valve sizes only)
• Z – Large Speed Scoop (1-1/2" & 2" valve sizes only)

Pro Series Critical Dimensions

* Distance from base of seacock to bottom of TH head with minimum safe thread engagement of 5 threads.

Hose barb inner I.D.

Standard Pro Series Valves & Seacocks

Common port styles, directions and flow patterns, pre-assembled and stocked. Each configuration is listed for mushroom, flush, screened mushroom and screened flush thru-hulls. Extra-long buttress thread thru-hulls are available for all Pro Series valves.

Threaded base (inline) Pro Series valves

Retail Seacock Pack & Pro Series Options

Seacock, thru-hull & connector retail pack

A 4-part kit: Pro Series valve, 90° hose barb connector, straight hose barb connector and a mushroom head thru-hull with buttress thread, to avoid thread-style mismatches on aftermarket installations.

Engine flush-out valve, locking handle

• 930136 – optional handle lock for 1"(25.4mm) & 1-1/4"(31.75mm); 930137 – for 1-1/2"(38.1mm) & 2"(50.8mm). Factory installed only, not a retrofit item; padlock not supplied.
• Anti-venturi thru-hull: add a "V" to any Pro Series part number.

Y-valves and Flowtech racing valves

Y-valves should not be installed below the waterline: Pro Series Y-valve seacocks are made for that. Forespar valve components are not compatible with any other manufacturer's product.

Vented Loops

• The loop goes between a water pump and any tank, head, engine or other system; when siphoning starts, the duckbill valve lets air in and breaks the siphon.
• Inspect and clean the rubber duckbill vent regularly. The vent barb option lets you run an external tube so odors are not released in the cabin.
• Also available in white (W suffix).

Installation Notes

• Pro Series seacocks install onto Pro Series buttress thread thru-hulls, or can be ordered for NPSM thru-hulls. A backing block on the inside of the hull is recommended; prepare the threads of both thru-hull and seacock with marine sealant.
• All other Marelon threaded connections are straight NPSM: mate with NPSM parts using teflon tape or marine thread sealant. NPT parts can be used with a liberal application of marine sealant, but Forespar does not warranty this usage.
• BSP threads are incompatible with NPSM; BSP versions are available by special order.
• Thru-hull connectors must be installed with proper bedding compound; maximum torque 20 lb/ft for Series 250, 251 and 253.
• If a thru-hull is installed less than 6"(152.4mm) above the waterline, a ball-valve or seacock must also be used.
• Valves are a maintenance item: actuate the handle regularly and lubricate the seals; each Pro Series valve can be disassembled to clean it and replace the O-rings.