Clean Agent Systems - Inspection, Testing and Maintenance

Posted by ORR Protection on Sep 30, 2020 7:30:00 AM

During the MCFP Virtual Conference series, expert Lee Kaiser, covers the basics of testing clean agent systems within your building. In the video below, watch as Lee dives in-depth on what clean agent systems are as well as how we test and view a system discharge. 

Video Transcript:

We find out the inspection test maintenance requirements for clean agents by looking in NFPA 2001, the standard on clean agent firing extinguishing systems. Specifically Chapter 7 has the ITM requirements. 

Let's start at the mechanical side by looking at the agent cylinder twice a year.  We're supposed to inspect the pressure gauge on the cylinder, and if we see a loss of pressure then we know that the cylinder's leaking.  We need to take it out of service, back to the shop, rebuild the valve, figure out why it's leaking and recharge the cylinder with agent.  We also need to measure the amount of agent in the cylinder. We need to use whatever level measuring device we have available to us and if we see a loss of agent, more than 5 percent, we also need to take it back. Those two typically go hand in hand.  If we've got a loss in pressure, we will also have a loss of agent. 

We measure the agent because when our fire suppression gasses get put in the cylinder and then we put in a specific amount of agent, and that's specifically designed for the applicant.  Clean agent systems are volumetrically dependent, so we calculate the amount of agent that's required, put it into the cylinder and then compress it with nitrogen.  Nitrogen, when it gets added to that fire suppression gas, condenses from gaseous phase to liquid phase.  It acts like there's a tank of water in there except it's the liquid agent, and we measure where that liquid level is. 

The top of the cylinder is called head space. There will be nitrogen gas at the top and then the rest of it will be the condensed fire suppression agent.  That's how we measure the amount of agent in the cylinder.  This gentleman with the yellow device, that's a factory installed liquid level indicator or liquid level measurement device, and through that device, it measures the amount of liquid in that tank. Then we measure against the installation drawings if there is right amount of agent for the space. 

There are some systems that are not specified or included, so when that's not there, you have one of two options.  The way that we've done it for years is; disconnect the cylinder from the piping, and move it over to a scale and weigh the cylinder.  We have a number of technicians that have long-term back issues from years and years of moving these big heavy cylinders, so we want to discourage anybody that's specifying systems from not specifying LLI's. 

There's another option that doesn't require weighing of the cylinder and that's with this device.  This is an ultrasonic liquid level indicator made by Coltraco and with this device you can take a straight-walled cylinder. I don't fly around with a pressurized cylinder, so I'm just using this cup today.  With the ultrasonic level indicator you get a reading up in the headspace where there's just gas and you move down slowly and wait for that reading to have a big change which indicates you're below the liquid level.

Then the technician will come back slowly and establish precisely where that liquid level is and they'll make a mark with a sharpie marker, get out the tape measure and establish the exact amount of agent for that specific cylinder using the manufacturer's manuals for that cylinder. This is a safer way to do that. It also works for high pressure carbon dioxide bottles and works for the different clean agent bottles if they're a straight walled cylinder. 

Once we have those two things done, we complete the container tag on the cylinder with this type of information.  We also visually inspect if the container is securely mounted to the wall because we don't want it to move.  When the system discharges, there can be thrust in the system and if any of those piping joints break for one reason or another, we don't want the cylinder to move. We also need to verify the location of the cylinders with the record drawings. If somebody gets aggressive with a pipe wrench and a little piping know-how, they could move one of those cylinders.  We want to make sure on the approved drawings the cylinder's still in the same spot so that we know that the system design is still adequate for the space. 

Every 5 years there's an external visual inspection required for the cylinders, so we want to make sure to inspect the cylinder for damage from the outside.  There's a special inspection report that gets filled out during this 5-year external visual. A technician that's doing this inspection will follow the compressed gas association pamphlet, but they're looking for issues of corrosion on the outside of the cylinder.  Any cuts or gouges on the steel, dents that were caused by somebody hitting it with a forklift, obvious leaks, or fire damage if somebody welded around the cylinder and damaged it is covered in an external visual inspection.  If we find any damage, then that cylinder needs to be taken back to the shop and additional internal inspections are needed to make sure that the cylinder is still serviceable.

Some systems use hoses to pneumatically release multiple cylinder systems, and those hoses need to be hydrostatically tested every 5 years according to the code. Hydrostatic testing is when we cap each end of the hose and fill it with water, we'll put it in a water jacket, fill it up to a certain pressure, and then if it holds at that pressure, great.  If it bursts at that pressure, then the water piece will make that a safe rupture.  The device will just get wet, and not get hurt from compressed gases that could be used instead of water. We don't use compressed gases to do this pressure testing, we just use water. 

For the protected space, clean agents need to be held in the room for a certain period of time to ensure complete extinguishment. Clean agents will extinguish in around 30 to 45 seconds, but the code says they need to be held in the room for around 10 minutes depending on the situation so that we can ensure extinguishment.  To establish that 10-minute time, we do something called the door fan test. It's an initial test that we do to measure the retention time of the agent in the room. Annually we don't do a new door fan test, we just visually inspect if there are any new things that would decrease the hold time in that room. We're looking for new penetrations in the room, new HVAC or duct work that comes into the room.  Are there any doors being held open, like this one in the picture here, and if the room size changed because clean agents are designed to install a certain amount of agent for the volume in that room, so if the room gets bigger, we may need more agent.  If the room gets smaller, we may have an over-concentration of the agent and we don't want that either. 

If we see any deficiencies, we need to try and correct them as best as we can, but if we're uncertain then our only remedy is to try and seal up the penetrations and do a new door fan test to establish the new hold time for the room. I want to go back to this picture for a second and you can see there's a door chock holding open this room. 

It's a pressured cylinder, so that's not a safe condition to start with, but let's look at this sign. This yellow sign on the door says caution, keep door closed, room protected by fire suppression agent.  Even though we're telling the people in that room that we need to keep that door closed it is still opened.  What state do you think that this picture was taken from?


Florida, yes, absolutely.  In the same facility there was another door where this was done correctly.  This is a door that's being held open with a hydraulic closer at the top and it's connected to a magnetic door hold device. This magnetic door hold device is tied into the release fire alarm panel, so when that system activates it disengages the mag lock and then the hydraulic closure automatically closes that door. 

"You hope it'll close."

That's a good point.  This gentleman here said you hope it will close.  We will verify that it closes through annual testing of the system. NFPA 2001 says we need to perform a system functional operation test following NFPA 72 where we would test control functions and in this case, we need to test the system discharge sequence on an annual basis. and We would find out through the testing of that sequence if the doors get that signal to open and if it's just one or two doors, we're just going to let them close and make sure that they actually works.  We test the initiating circuits and devices, and test the manual release. 

Clean agent systems all need to have one means of manual release of the system, if not more, installed. We test the abort switch if one is installed and test the releasing device activation, to make sure that it activates. The intent is not to discharge the agent. A lot of time you'll see a technician testing your clean agent system and the device hanging on the side of the tank via this flexible conduit which is the electric control head for that cylinder.  It normally sits on top of the tank and it's ready when it gets a signal to fire a little pin down which opens up that valve. We don't let it sit for the testing because if that accidently fires off we don't want to discharge the agent.

One of the first things a technician will do is put the system into a safe condition and remove the control heads. We test control head device activation by watching that pin fire, but we don't let it sit on top of the tank where it would normally be. We have information about supervisory devices to see if that control head's removed, but that's only installed on new systems nowadays.  It could be retrofitted to old systems, but as we talk about the existing systems, we don't go into that.

We suggest that you specify liquid level indicators for fast and easy liquid level measurement.  Remember we have to do that twice a year.  You need to provide remote displays, so we suggest that wherever you have a suppression control panel that is outside of the protected space, that there is some sort of display for that, usually through our remote enunciators.

That's one suggestion, and then a lot of these places that have clean agent systems that use advanced detection like air sampling or Vezda detection, and we suggest that you have remote displays for that Vezda detector outside of the space, so you can see remotely that there's smoke building up inside your protected area, and you can address it and try and investigate what's causing the smoke in that space. 

Topics: Featured Article, Featured Blog, MCFP

Featured Download

Subscribe to the Fire Protection Blog