What is the Oasis Hydrant Assist Valve?

Do you ever wonder why you couldn’t flow more from your engine or truck that was being supplied by a good city hydrant? Have you ever needed to lay hundreds of feet of LDH (large diameter hose) and overcome the friction loss to achieve an adequate flow rate? Were you able to address either of these concerns without interrupting your water supply?

The Oasis Hydrant Assist Valve is a simple answer to these issues that lets your crew set up for a boost without interruption.

In this article we are going to discuss the Oasis Hydrant Assist Valve, explain how it works, and talk about when you might use it.

What is the Oasis? 

The Oasis is a hydrant assist valve/relay valve with a half ball that offers unobstructed, full flow water ways and internal clapper that either directs the water to the truck at the fire scene or to the intake of the pumper that is going to boost. It can be installed directly on a hydrant or preconnected in a long LDH supply hose lay to allow you to maximize your flow and pressure.

The valve operates in two modes. Mode one lets you operate off a hydrant or any pressurized source to move water directly from the hydrant to your attack engine at the fire scene. This does not increase your pressure or flow but allows you to immediately attack the fire with a normal hydrant hook up. Mode two uses a secondary relay pumper and once engaged, moves the clapper to reroute water and allows you to boost your flow and pressure using the secondary engine.

Now that you know what the Oasis does, you may be wondering about the scenarios you might use it in. Let’s look at two examples.

Low Hydrant Pressure: 

When your intake pressure on the truck is reading close to zero, there’s a good chance you still have more water supply to tap into.  Remember hydrants are supplied by large water mains, and the intake pressure of your water supply is at the truck, not at the hydrant. When you want to get that extra capacity from your hydrant to the fire, you can use the Oasis to tap into that potential.

The Oasis allows water to move straight through the device to an attack engine when necessary. When a boost is needed or your second due arrives on scene, the intake and discharge lines can be connected, and the boost engaged to maximize flow and pressure to the fire.

The design of Oasis means you do not need to shut down to connect those added intake and discharge lines from the second due engine. Your crew can continue flowing water to the fire ground as the relay connects and use the benefits of the boost once Mode Two is engaged.

Long Hose Lays: 

Sometimes you need to connect to a hydrant hundreds of feet from the fire in a rural setting or do a long lay to connect to a hydrant on another water grid. Your second due can come in as a relay and shut down the line to connect an intake and discharge to boost pressure and flow, but that requires an interruption of water to the fire ground.  With a preconnected Oasis in your LDH lay you can connect and boost without shutting down the water supply to the fire ground.

To do this successfully, the Oasis needs to be placed between hose lengths when you lay your hose line. Water will flow straight through until a relay pumper connects and boosts flow. The Oasis valve design means your second due can connect and boost flow without interrupting water flow when it arrives.

This setup gives you the boost you need to overcome the friction loss of the longer hose lay.


With Oasis, your crew can keep water flowing to the fire, even when your relay pumper needs to connect. Whether you work from a well-fed hydrant or need to overcome the friction loss of a long hose lay, Oasis can help you keep the fire ground efficient.

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