Double Shut-Off Steel Plug 1/4", 3/8" and 1/2" FPT

The Double Shut-Off Steel Plug is a zinc plated steel quick connect plug in 1/4", 3/8", and 1/2" FPT, rated from 4000 to 5000 PSI depending on size. Valves in both coupling halves seal the instant you disconnect, so nothing drips and the line stays charged. In stock and ships same day from Sun Brite Supply in Gaithersburg, Maryland.

Product Overview

A standard quick connect dumps whatever is in the line the moment you pull it apart. A double shut-off plug does not. Spring loaded poppets sit inside both the plug and the socket, and each one snaps closed on disconnect. You get no spray, no puddle, and no lost prime.

That matters most when you are running more than one tool off a single supply. Wash bays, in-plant systems, multi-station trailers, and chemical lines all use double shut-off couplings for the same reason: you can break a connection mid job without shutting down the whole rig.

This plug is the male half of the coupling. It threads into your gun, whip, or manifold with FPT pipe thread, then snaps into a matching double shut-off socket. The body is machined steel with a zinc plated finish, which stands up to wet bays and outdoor trailer storage far better than bare steel.

Key Features and Specifications

• Double Shut-Off Design: spring loaded valves in both halves seal on disconnect, so there are no drips and no pressure loss
• Material: machined steel with a zinc plated finish for rust resistance
• Sizes: 1/4" FPT, 3/8" FPT, and 1/2" FPT
• Rated to 5000 PSI: the 1/4" carries the highest rating, see the size table below
• Ball Locking Sleeve: positive mechanical lock that holds under pressure and vibration
• Captive Seal: keeps the poppet sealed tight when the plug is disconnected and sitting loose
• Made in USA: per the manufacturer

Pressure Rating by Size

These are not all rated the same, so match the number to the size you are buying.

Compatibility

Double shut-off couplings are a matched system. The plug and the socket both carry valves, and both have to be double shut-off style for the connection to seal on both sides. A double shut-off plug will physically connect to a standard straight-through socket, but you only get one side sealing, which defeats the purpose.

• 1/4" FPT for gun inlets, small whips, chemical lines, and low flow accessories
• 3/8" FPT for most gun and hose connections on professional machines
• 1/2" FPT for main supply lines, manifolds, and high flow systems

Match the size to the port you are threading into, not to the hose you think you need. A 3/8" plug will not thread into a 1/4" port no matter how much you lean on the wrench.

Applications and Use Cases

• Multi-station wash bays where several operators share one pressurized supply
• Chemical and soap lines where a disconnect that sprays is a safety problem, not just a mess
• Hot water rigs where dumping the line means losing heat as well as pressure
• Tool changes mid job when switching between guns, surface cleaners, and extension wands
• Trailer and skid plumbing where a manifold feeds several outlets

Installation and Maintenance

Wrap the male pipe threads with PTFE tape or brush on pipe sealant before you thread the plug in. Snug it down with a wrench, but do not crank on it. Over-torquing a fitting into a cast port is how ports get cracked.

Wipe the face of the plug before every connect. Grit sitting on the poppet is the number one reason a shut-off fitting starts to weep, and it is a lot cheaper to wipe a fitting than to replace one. Keep a rag in the truck for this.

If a coupling gets hard to connect or will not release, do not force the sleeve. Dirt or light corrosion is binding the balls. Clean it with a wire brush, work a drop of silicone lubricant into the sleeve, and cycle it a few times.

Check the seal on the plug periodically. A weeping connection is usually a worn seal, not a worn body. If the sealing surfaces are scored or pitted, replace the plug rather than trying to dress the metal.

Frequently Asked Questions

What is the difference between a double shut-off plug and a regular quick connect plug?

A regular quick connect has no valve. Pull it apart under pressure and the line dumps. A double shut-off plug has a spring loaded valve inside, and so does its matching socket, so both sides seal at the moment of disconnect. Nothing sprays and nothing drains.

Are all three sizes rated the same?

No. The 1/4" is rated to 5000 PSI, the 3/8" to 4500 PSI, and the 1/2" to 4000 PSI. All three are good to 300 F. See the table above.

Can I use a double shut-off plug with a standard socket?

It will connect if the size and coupling standard match, but only the plug side will seal. To get the full benefit you want a double shut-off socket on the other half.

What size double shut-off plug do I need?

Check the port you are threading into. Most professional gun and hose connections are 3/8" FPT. Smaller accessories and chemical lines usually run 1/4" FPT. Main supply lines and manifolds on higher flow systems run 1/2" FPT.

Why is my double shut-off coupling leaking?

Nine times out of ten it is debris on the poppet or a worn seal. Disconnect it, wipe both faces clean, and reconnect. If it still weeps, inspect the seal and the sealing surfaces for scoring.

Where can I buy pressure washer quick connects near Gaithersburg, Maryland?

Sun Brite Supply is located at 16620 Oakmont Ave, Gaithersburg, MD 20877. We carry a full selection of pressure washer quick connects for walk-in customers and ship nationwide. Local contractors in Maryland, Virginia, DC, and the Mid-Atlantic area can stop by for same-day pickup. If you are outside the area, order online at sunbritesupplymd.com and we will ship it out fast. Call us at 301-519-9274 if you need help finding the right part.

Before You Order: What to Check

• Port size and thread type: measure the port you are threading into. FPT is female pipe thread, not a hose thread.
• Matching half: confirm the socket on the other side is also double shut-off, and the same size.
• Pressure and temperature: check the size table above, the three sizes are not rated the same.
• Old part comparison: if you can, back the old fitting out and compare it side by side with the specs listed here.
• Still not sure? Call us before you order. Five minutes on the phone beats a return.

Why Buy Your Quick Connects from Sun Brite Supply?

Sun Brite Supply ships from our warehouse in Gaithersburg, Maryland. We stock the same parts the pros run, and every part we sell has been vetted by people who work on this equipment every day. No knockoffs, no mystery fittings that round off the first time you put a wrench on them.

Need help picking the right part? Call us at 301-519-9274. You will talk to someone who actually knows pressure washing equipment, not a script reader at a call center. Our team has over 50 years of combined experience in the pressure washing industry, and we can verify fitment, suggest alternatives, and get you the right part the first time.

Local to Maryland or the DMV area? Stop by our Gaithersburg location at 16620 Oakmont Ave for walk-in counter sales. We can pull parts, check fitment in person, and get you set up on the spot.

We carry over 2,700 pressure washing parts and accessories in stock. Pumps, hoses, fittings, nozzles, chemicals, engine parts, burner parts, and electrical controls. Most orders ship the same business day when placed before 2 PM Eastern, so whether you are in Virginia, Pennsylvania, DC, or across the country, you get your parts fast.

Shop online at sunbritesupplymd.com or call us directly at 301-519-9274. Over 2,700 parts ready to ship.

Pair this plug with a matching double shut-off socket and a length of pressure hose so both ends of the connection seal the same way.

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