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Water PRV Sequence of Operation

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A High-Performance Water Pressure Reducing (PRV) Station requires valves that are properly sized for the flow rate and pressure drop of the zone they serve.  Also, the High Flow and Low Flow valves must have the proper pressure setpoints to balance the flow rates across them.  Cougar USA can help in the design, installation, and start-up of PRV’s to ensure constant pressure to the fixtures downstream of the PRV Station.

Water PRV Sequence of Operation Tech Talk Transcript:

Hi, I’m Tim Zacharias with Cougar USA on this Tech Talk, we’re going to be covering the sequence of operation for a Water Pressure Reducing Valve station or PRV station.

For this example, we are looking at a PRV station here that’s designed for a high-rise building. We’re generating a lot of pressure with our booster system, down the lower floor to be able to have usable pressure up at the top of the building, and in the lower floors, we’re having to knock that pressure back down to get it below 80 PSI.

So, for this example, our low flow PRV is going to be set at 70 PSI, our high flow will be set at 65 PSI, and our relief valve and pressure switch here are going to be set to 85 PSI, so 15 PSI above our set point. So, 70 PSI, 65 PSI, and 85 PSI here. The relief valve can’t be set to higher than 100 PSI by code, so usually, 15 to 20 PSI above your low-flow valve is where that set point is going to be. We’re going to start the sequence, assuming there’s no flow in the building, so both valves pressures are satisfied, we have no flow going through the valve system, and they are shut. Once you start to get a little bit of flow through the station here, let’s say it’s serving a few floors, a few restrooms kitchen, things like that, you start to see some activity. We’re going to see the pressure drop off and our low-flow valve here is going to start controlling it at that 70 PSI, so it’s going to modulate open close to maintain that 70 PSI going through the valve.

Now, as the flow demand increases, that flow rate increases, the low-flow valve is not going to be able to keep up and the pressure is going to start to drop off and once that pressure drop gets down to about 65 PSI your high flow valve is going to open up and start to control at the 65 PSI. So our low flow valve is all the way open, and we are controlling with the high flow valve here at the 65 PSI. Now, this one is going to continue to control until it’s satisfied. So, once the demand starts to slow down and the pressure is going to rise up again, and once this valve is satisfied at 65 PSI, it will close, and this valve will take over controlling at the higher pressure. Once that pressure comes back up, it will start to control again at the 70 PSI until there’s no flow and then it will shut off as well, and that cycle is just going to repeat as you have changes in flow rate across the system. Low-flow valve handle on the overflows; high flow in the high flows there.

Now, if you have an upset condition where one of these valves fails, it will fail open, which will allow the high pressure to come downstream. You’re going to see the relief valve open up at that 85 PSI and start to relieve the pressure and dump water to drain. At the same time, we’re going to sense that pressure here with the pressure switch and that is going to send the signal to our control panel here that I can simulate with the button and that is going to after that time delay it is going to close the block valve.

Now we have the time delay in there so that, you know, a short over-pressurization that is not caused by a failure valve won’t kick off this sequence, it has to be sustained in order to trip the alarm. So once the alarm is triggered here, it’s going to send a signal to the building automation using an output there and it’s also going to close the motor-operated butterfly valve or ball valve there that is our block valve. It is going to hold that valve closed until it is manually reset. So if we are to have this pressurization event and we allowed the valve to automatically reset. As soon as the valve closed, the pressure would drop downstream, the pressure switch would sense that, and send a signal to the control panel. It would allow the block valve to open. The block valve would open, we would have high pressure coming back thought. It would go through the field PRV, hit the relief valve again, over pressurize, hit the pressure switch. It would send a signal to the control panel, which would close the block valve again and you just be stuck in this circle of opening-closing the block valve, basically trying to maintain pressure with an MOV and that’s not going to be a good application or good control method for doing that.

So instead once we sense that high-pressure, we close the block valve and hold it close until it is manually, reset and opened. So before manually, resetting it, we want to close the downstream valves there, and then, press to reset. That’s going to open our block valve, allow the high-pressure to come up to these isolation valves here, and then at that point, you could slowly open these up, refill Downstream with water and see if the pressure goes past its set point. If it does, you can leave that valve closed and you can open up the other valve and allow it to control. Now, you can isolate this valve completely, do your service on it, and while you still have water flow through the other valve.

So, that is the breakdown of the sequence of operation for a Cougar Systems Water PRV station. If you have any questions, please feel free to reach out or check out the other videos on our website.

Thanks

Storm Sump Pump Stations

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Storm Sump Pump Stations protect the lower levels of buildings and parking garages from flooding.  Check out this Tech Talk on the application and design of Storm Sump Pump Stations.

Storm Sump Pump Stations Tech Talk Transcription:

Hi! I’m Tim Zacharias with Cougar USA. In this Tech Talk, we’re going to cover storm Sump Pump Station applications.

So when we’re looking at a storm sump application this is going to be anything in a building that’s collecting water from a clean source, rain, groundwater, condensate from Air Handlers, or fan coil unit, things like that. And it’s going to be in the typical locations in a building: at basement, parking garage, loading docks, spots where the water’s going to collect. We are typically going to recommend in this situation an N+1 design, meaning, both pumps can handle, one hundred percent of the load coming into the Basin. But in Houston, unfortunately, we have these high rainfall events where it might be normal or require two pumps to run in certain situations, so that’s going to affect the type of float switch assembly that we use and some of the programming so that we can run those two pumps with or without alarms.

So one way to do that is with a 4 float system in the Basin with a lag pump counter. It is going to allow us to run both pumps without getting a high-level alarm. But with that lag pump counter, we’re going to be able to see how often that pump is coming on and give an alarm if it’s over the threshold.

The type of pump that we are going to recommend for this application is going to be a large, non-clog-style pump. So, that’s going to be either a Vortex or an open Channel type impeller. They can still handle some solids, but they’re going to be able to move large volumes of water, typically into a gravity main type of discharge.

So what are these components that make up a storm station or Storm Sump Pump Station? the design here on the screen is what we would consider a typical sump pump station or duplex application. Using submersible pumps instead of a column style or extended shaft style Pump, we’re going to have a control panel and level float switch assemblies to be able to give that indication of the level in the water and then turn our pumps on and off, and give alarms. Also, we are going to have a lift-out rail system, for those submersible pumps so that they can connect to the discharge piping easily, but still be removed out of the pit for service and things like that for access.

We are also going to recommend, obviously, the isolation valve and some check valves like we’re showing them here through the discharge out of the top. It’s nice to be able to access them outside of the wet well. You could also do a valve box off to the side here with a separate access hatch for those valves to be able to get to them without having to get into the wet well. If there are space requirements and it does have to be inside the wet well, they will work there, just a little bit tougher to access them for maintenance.

The last piece is going to be the cover and that hatch is going to provide safety over the top of the pit and prevent Open Access into the wet well. It will also give you some structure and stability for the upper guide brackets of the rail system attaching there so that the pumps can come up and straight out the top of that hatch to be serviced.

So, that is what we want to cover on our Storm Sump Pump Station applications. Check out other Tech Talks for more information for feel free to reach out.

Flood Protection Valve

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Rain isn’t the only way a building can flood. If there are Domestic or Fire Water Storage Tanks in the building, a flooding risk is always present.

Cougar Systems Level Controls constantly monitor for High Level and actuate a motorized valve to shut off the water supply to prevent overfilling the tank and flooding the space. 

Flood Protection Valve Tech Talk Transcript:

Hi, I’m Tim, Zacharias with Cougar USA. In this Tech Talk, we will cover flood protection valves for fill stations and atmosphere storage tanks. In the city of Houston, we have the requirement to go through the atmosphere storage tank before we add booster pumps into our building. So, a lot of these are going to be installed on the first floor, maybe in a basement on a vault outside, and we want to prevent those tanks from overflowing and flooding the building.

In order to do that, we have level sensing devices in the tank there sending that level read out to the level control panel like this. We use a motorized butterfly valve Upstream of our fill valves as our Safeguard to prevent the tank from overflowing and flooding the room.

So we have the high-level alarm set based on the height of the tank in inches, and once that level is reached, it’s going to signal the high-level alarm, as well as trigger the block valve. Now the block valve is going to stay closed until the tank level is drawn down, and then it will reset the high-level alarm, open up the block valve, and if one of the fill valves has failed and is still allowing water in the tank, it will refill and hit that high-level alarm again and trigger the block valve to close, so, your block valve will essentially act as a backup fill valve, but it’s going to trigger that high-level alarm every time which is one of the reasons we definitely recommend monitoring that high-level alarm with the building automation so that they can get those alarms and that feedback that the block valve is on. So we prefer using the butterfly valve with the motorized operator for those two reasons,

The other alternative is to use an electronic Cla-Val like this one 3601 that we use for the fill valve. This makes a great fill valve because we have constant or regular flow through the valve, through the fittings, in the solenoid that keeps them clear of trash and debris and allows for that diaphragm to load and unload every time.

So if we have one of these solenoid valves, this 1-3601, as the block valve, it’s going to sit in the open position most of the time, and it’s going to have water flow through the body of the valve, but not necessarily through the tubing and through the solenoid. So, you could have trash build-up on the solenoid or somewhere in the strainer there, or anywhere else in the pilot, things like that. So when you do get the high-level arm, and you do need to close it, this valve will send power to the solenoid, which is going to try to open up and load water onto the diaphragm to close it.

Now, if water can’t get into the tubing or through the pilot, that’s not gonna let water on the diaphragm and allow it to close. The other issue we would have is that the solenoid valve requires constant power, in this case, 120 volts to hold the valve closed. So if we had a loss of power or an issue with the control panel or even if the solenoid failed. Any one of those three, you would lose power to the solenoid and the valve would go back to its normally open position, and then you would overfill your tank. With the motor-operated valve, the butterfly valve can sit for long periods and not have the issue of being able to close because it’s been sitting open for long periods. Also, with the motorized actuator here, we send one signal from the control panel to open the valve and a separate signal to close the valve. Once it is in the open or closed position, it will stay there until we send the second signal to move again. So we’re only sending a signal to move the operator, not to hold it in the open or closed position.

If you have any other questions about the flood valve or the flood protection valve and why we’ve gone with the butterfly valve in the motorized actuator, please feel free to reach out or check out other Tech Talk videos for more information.

Thanks.

Cougar USA has worked in hundreds of buildings in Houston with break tanks, level controls, and booster systems. For more information or a free building assessment, contact us here.

Monitor City Pressure

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In the city of Houston, we’ve had two major interruptions in water supply in the last 18 months. Unfortunately for many buildings, they didn’t find out until their tank and piping were dry and it was too late to act.

With a Level Control Panel from Cougar USA, you can monitor incoming city water pressure and receive an alarm as soon as the pressure drops, giving you time to conserve water and warn patients, tenants, and guests of the situation.

Monitor City Pressure on Fill Stations Tech Talk Transcript:

Hi I’m Tim Zacharias, with Cougar USA. In this Tech Talk, we’re going to cover Monitoring City Pressure on your fill station so when you have a flooded suction application, like in the city of Houston, where we have the code requirement to go through an atmosphere storage tank, like this before your booster pumps.

If you lose City water, then a lot of times, the only indication that you would have or the only warning that you would have would be a tank low-level alarm. So that would mean that you’ve lost city water you’ve drawn your tank all the way down. You get your low level from the panel and that’s almost too late for that’s really when you’re out of water.

So if you’re monitoring City pressure coming in on the inlet of your fill station and you lose City pressure, that’s going to be a really early indication that you might have an issue that you’re going to, you know, probably run out of water and then be able to make changes to mitigate that.

To simulate that here on our control panel, you can see that we have the read out of what the city supply pressure is coming in so you know being fair here at 40 PSI for the City of Houston. A lot of times we have pretty low pressure but if that drops down below, our set point, what’s going to happen here is we’re going to get the low supply pressure alarm and, this is adjustable, Ss have a little bit of a delay there. Just in case we have a blip in pressure, is not going to give a false alarm. But once we get that low-pressure alarm, you can see it doesn’t actually stop to fill valves from filling or anything like that. It’s just going to be an alarm output to the building automation, to let you know that you’ve got low City pressure so that you can silence it there and then it is adjustable here under the alarm settings, what that supply pressure is, so that can be adjusted as well.

So once the city pressure is restored, the alarm clears and everything is back to normal, but again, monitoring this incoming City pressure is a great way to give yourself an early heads up that your building is going to lose water and especially monitoring this, so that you’re getting those to the building automation. You can do that through what we call a Fail-Safe dry contact where you’re going to get the alarm if you have either an actual alarm, a power failure, or control power failure, we can also do communication over in a back net so that you can actually get the readout of the city pressure is as well as the alarms.

If you have any questions, please feel free to reach out or check out other videos.

Thanks.

Cougar USA has worked in hundreds of buildings in Houston with break tanks, level controls, and booster systems. For more information or a free building assessment, contact us here.

A personal story of living Cougar’s mission

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Cougar USA’s mission is to make buildings work, so the people inside can do theirs. Over the last few months, this has become a personal mission of mine as well.

In November, my son Joey was born at Texas Children’s Hospital Pavilion for Women, and earlier this month had surgery in Legacy Tower to remove a benign cyst from his abdomen. Thanks to the amazing doctors and staff at TCH, Joey made a quick recovery – he definitely handled the surgery better than my wife Ashley and I did! After spending a few days recovering in West Tower, Joey was back smiling and being his happy self. Ashley and I feel very blessed that Joey’s case was minor compared to many families at Texas Children’s.

I have worked at Cougar for almost 12 years and I have always appreciated what our systems are used for in buildings, but it wasn’t until it was my son who needed them that I truly felt the impact of our work. It was a great feeling to know that Cougar helped provide the systems and services for the building’s operations.

Pictured on the left are the Texas Children’s Hospital Buildings we were in for delivery, surgery and recovery. Pictured on the right is the view from our recovery room in West Tower looking north down Fannin. Cougar has systems in almost all of these buildings, even the ones off in the distance on the right.

This experience with my son has made me proud to be a part of the Cougar team. I believe the best way I can serve our customers is through the Cougar USA Training Center, helping Consulting Engineers, Installing Contractors, and Building Engineers design, install and maintain water control systems in commercial buildings.

Like my son’s surgery, I know Cougar is a small part of the big picture in the daily activities of the Texas Medical Center; but for those few days in the hospital, there was nothing more important to me and my family. Not only do I feel lucky to have a happy, healthy baby boy, but I also feel honored that I can serve these hospitals every day and pay it forward to other families. The doctors, nurses, and staff at TCH (and throughout the Medical Center) perform miracles every day and Cougar works with our partners to make sure they have a place in which to do it.