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Alternators - Mercury

1/2" Water Pressure Dump
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1/2" Stainless Steel In Line Pressure Relief Valve Water Dump


This has to be one of the coolest and simplest stream lined inventions to come along in recent times. High water pressure spikes plague numerous boats and cause catastrophic engine damage. Until now your only option was an independent pressure relief valve that you then had to plumb to a water dump to discharge the water. Thanks to the Hardin Marine team they have taken the best high flow water valve design and integrated it into a common water dump.

These dumps feature a sleek design as well as unique wrench flats machined into the body aiding in assembly during a one person installation. Constructed from 316L stainless steel. This model provides a 1/2 NPT female thread allowing for any arrangement of possible fitting and hose connections. The unit features a stainless tulip style valve that is spring loaded. The units come preset at approximately 10psi.

  • 1-7/16" Flange Diameter
  • 1/4" Flange Height 
  • 1-1/8" Shaft Outside Diameter
  • 3" Overall Length
  • 1/2" NPT Internal Thread
  • Pre-set at Aprox. 10lb Pressure Relief 
  • Approx. Flow Rate (gallons per minute) 10 psi=7 GPM, 15 psi= 13 GPM, 20 psi=19 GPM

1-1/4" Pressure Relief Valve Fitting For Inline Use, 1/2" NPT
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1-1/4" Pressure Relief Valve Fitting For Inline Use, 1/2" NPT


1-1/4" Pressure Relief Valve Fitting For Inline Use, 1/2" NPT

This valve should be used in conjunction with the 128-5000 pop off valve.

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  • 101211-3020
  • 101211-3021


  • 9-19200

Mercury Marine

  • 821663
  • 821663A1

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Additional Details:

  • Fits: All Mercury Verados



  • 20860


  • 9-19202

Mercury Marine

  • 892940T
  • 892940T01
  • 892940T02

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Key Features:

  • 5S/I 50 amp

Additional Details:

  • Fits: 1.5L and 3.0L
  • For: 200 DFI, 200 DFI/DTS, 225 EFI, Sea Pro, 225 DFI/DTS, 250 EFI



  • 20850


  • 9-19201
  • 9-19204

Mercury Marine

  • 828506
  • 875286A1
  • 875286T
  • 881247A1
  • 8M0064020

Mercury Sport Jet

  • 881247A1

Pressure Relief Valve
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High Performance Marine Water Pressure Relief Valve


High Performance Marine Water Pressure Relief Valve

This high performance pressure relief valve system was specifically designed for the highest of performance applications where high speeds and high water pressure run hand in hand. Extensive testing in boats with speeds in excess of 170MPH have proven this design to be the ultimate answer to solving the issues of bleeding off high volumes of water. The problem with standard pressure valves is that they can reduce pressure spikes but they cannot move volumes of water. Hi performance marine applications need to move massive volumes of water. The nearly 2" stainless steel valve is larger and more capable than any fluid control system available today. Besides the ability to move massive distribution of water this valve provides precision adjustable water control. Water control is designed or set to open at a predetermined set pressure to protect against excessive pressure in the engine block, cooling system, and sea strainer. 

This unit features dual stage manual monitoring capability. Besides accepting the pressure signal from the water flow entering the massive dual 1"NPT water inlets there is a secondary chamber that can be plumbed to a secondary signal source (Example:engine block) If the pressure were to rise in the engine block it would provide the pressure signal through the plumbing to the water pressure control valve and the pressure is relieved by allowing the pressurized fluid to flow from the bottom chamber passage out of the 1"NPT discharge. There is not other system available like this today.This compact, highly accurate, high performance direct acting pressure relief valve can be manually adjusted to a desired opening pressure and/or flow specifications. External adjustment provides ease of use for rapid pressure changes. Manufactured from brass, Hard coat billet aluminum and 316 stainless steel. This valves feature a Quad ring seal which provides for extreme accuracy and repeatability.

• Accurate and Repeatable Pressure relief 
• 100% Factory assembled and Tested 
• 95-98% of Pressure retention 
• Maximum Adjust ability 
• Excellent Performance 
• Compact Size 

 Technical Data 
• Set Pressure Range: 7. to 40 Psi 
• Remote Inline Valves Series (RIVS)

Jet Drive Water Pressure Relief Kit
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Standard Hose Kit for Water Pressure Relief Kit


For use with plumbing outlet 150-5000 Water Pressure Relief Kit to dump overboard. Includes:
  • Brass 1/2" NPT x 5/8" Hose Fitting
  • Plastic 5/8" Hose Water Dump
  • Two Stainless Steel Hose Clamps
  • Three feet of 5/8" Water Hose

Jet Drive Water Pressure Relief Kit
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Water Pressure Relief Kit


Jet Drive Water Pressure Relief Kit

The kit from Pack-A-Jet will come with a brass pressure relief valve with 1/2" npt bypass outlet and a stainless steel extension tube for easy installation. Direct fit to the Berkeley models 12JC and 12JG 3/8" npt water inlet, but can be used on other models as well.

The pressure relief valve opens at app. 12 to 15 psi to move excess water overboard.
Optional hose kits are available see related products below.