What Is the Difference between a Wet Barrel and a Dry Barrel Hydrant?

Interviewer: Is there anything else you would like to discuss?

Dry Barrel Hydrants Are Installed in Cold Weather Areas

David Munoz: I wanted to talk about the difference between a wet barrel and a dry barrel. They usually put dry barrel hydrants in cold weather regions. The reason is that there’s only water all the way to the shoe of the hydrant, which is at the collection at the very bottom below ground.

Those are called dry barrels because what you see above ground, there’s no water above up to the top of that head. The difference in a wet barrel is there’s water all the way up to the top of the head.

It Is Important to Properly Maintain a Wet Barrel Hydrant

In Arizona, they use both because it doesn’t really get real cold here and it gets hot. It gets warm, but that’s why a lot of them they use the wet barrels. Those actually need maintenance as well. Those have individual valves for each one of the nozzles. For each nozzle, actually, that’s the control valve for each one of those nozzles on a wet barrel. On a dry barrel it’s usually just the operating on top. Those are the difference.

Interviewer: Will a wet barrel not work in cold weather or will it require more maintenance?

Wet Barrel Hydrants Can Freeze in Cold Climates

David Munoz: For an example, if you lived in Alaska, you don’t want to have a wet barrel hydrant because you have water all the way to the top of the head, so they’ll freeze and they’ll break.

In cold countries you want to have dry barrels hydrants. That means there’s no water above the ground. It’s actually below ground at all times. When you have a bad hydrant that has lack of maintenance in cold weather conditions, normally they leak through the main valve rubber inside the hydrant and water will start climbing up that barrel.

When it gets cold, the hydrants will freeze and then they’ll break on top. That happens pretty often in cold climates. Or, they become frozen in the very top and then when they are needed they’re frozen because they have a bad main valve rubber because of lack of maintenance.

Interviewer: You work primarily in Arizona only?

David Munoz: I work only here in Arizona.

Post Indicator Valves Control Fire Lines to Buildings

We also work with post indicator valves. They look like little red stamp pipes and they are usually in the commercial buildings on the parking lots. They usually have a little glass window and they’ll say open or close. It kind of looks like it has a handle on the side. Those are post indicator valves.

They are the control valves for the fire lines to the buildings. There could be one if they have one fire line and one straight line going to the building. Or if it loops around the whole entire building, in that case, you might see several.

We also do repairs on those as well because those also require maintenance. They have to be lubricated because when you are operating them, you’re turning that handle and turning that valve below ground. That’s what operates that valve below ground.

Post Indicator Valves That Are Not Maintained Can become Stuck in the Open or Closed Position

If you do not perform maintenance on those post indicator valves, you’ll come to a point where you are trying to turn one and they won’t also turn. They are stuck in the open position or stuck in the closed position depending on where they broke at that time.

Interviewer: What do those lines feed in the building?

Post Indicator Valves Are a Fire Code Requirement

David Munoz: They usually feed the fire lines. The reason the post indicators are there is for the fire department. When they’re coming in they can look at a post indicator valve and it can tell them if that line is open or closed position because it has an indicator. The indicator says open or closed. That is a requirement from the fire code.

Interviewer: If you’re going to draw water from a hydrant or from sprinklers and there’s a short back in the system. Will the whole system not work?

David Munoz: Yes. For an example, you’re going to have a tie in coming in from the street and it’s going to feed your whole building. Let’s say it is a retail store. That fire line is going to go towards the front of the store, it’s going to go around the whole back and front again.

It’s going to tie back in and maybe tie back in somewhere in the street again. So it’ll have a 2 tie in group for that whole building. On that line itself, they have control valves to shut that line down and you’re going to have several valves, so you can actually little sections whenever part breaks.

Since it’s a commercial building, they can’t have those small valve boxes you may have seen. A commercial building has to have an above ground valve so they can tell the fire department that they’re open or closed, at that present time, when they do the inspection.

To Avoid Damage from a Waterline Break It Is Important That the Post Indicator Valves Are Operational at All Times

It is very critical that those work as well. Those are regularly tested as well. You have to actually operate those to make sure they’re functional every year just like you do a hydrant. Because if they don’t function, there’s no way you can turn off that fire line. If the waterline breaks between the street and the building, then you’re going to have some damage to your facility.

Private Facilities Are Responsible for Maintaining the Post Indicator Valves

Interviewer: It’ll be the facilities responsibility because the property is not owned by the city?

David Munoz: Absolutely. It’s the facilities responsibility. If they don’t operate and there’s no other valves before that, they could be isolated to isolate their section. Then you have to call the city that you live in, so they can isolate their line to make sure they turn you off so you can do the repairs.

Some cities will have valves that might be in conflict with other buildings. Then all of a sudden you have other people out of water. This is why it’s important that all these get inspected every year.

A Regular Maintenance Contract Includes Inspection of the Hydrant, Control and Post Indicator Valves

Interviewer: When you do a maintenance contract, do you typically just do a hydrant maintenance one or do you include the control and post indicator valves?

David Munoz: No. I like to do the hydrant maintenance and the post indicator valves on an annual basis. The contract will be set based on what’s wrong with that hydrant. On an annual basis I’ll go in, do the inspections and I provide the property manager or owner with inspection reports.

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