I recently went out to look at an 8" double detector check that needs to be relocated and replaced. When I went inside to get some info off the riser plate, I noticed that there was an air compressor piped to the sprinkler system. Not being and expert on fire protection, can anyone explain to me how these systems work.
the dog :cool:
I don't do sprinklers but it sounds like you will be working on a dry pipe system. The system is charged with compressed air. When a head opens up and the air is lost a valve opens and lets the water in.
Due to trade agreements between the different crafts the only systems I work with are small wet ones. However, it is our responsibility to test and maintain the backflow preventers protecting the potable water supply from the fire lines.
There should be a control valve between the back flow preventer and the fire sprinkler system. The control valve, if I am correct, is the valve that allows the water to flow into the system if a head pops open and the air pressure in the line suddenly drops. The compressor, as Utah mentioned, holds this valve closed when tiny small leaks or expansion and contraction cause the air pressure in the lines to flucuate..
Depending on the design of the system there is sometimes a valve between the back flow preventer and the control valve to allow for service of the systems to be made with out a lot of headaches. These are usually chained open to prevent tampering and incompetent mistakes. Generally when testing these devices we arrange for a fire saftey representitive to be available in case of problems, particularly in large buildings full of people. In schools, fire saftey drills are scheduled in conjunction with our certification of the systems. This way the alarm sytems can be tested at the same time as the backflow preventers.
There should be a record of who originally installed the system, and my course of action would include talking with them if I am not sure about isolating the backflow preventer.
On this subject, there was a 12 inch RP device with bad valves on both sides and a bad main valve from the water main I was scheduled to replace over the Christmas weekend last year. This was the first device installed in the mechanical room in a very large processing facility. Over the course of decades many, many systems had been installed on top of, in front of and even downstream of this device. I was to have a 48 hour window to remove and reinstall everything.
It was going to be tight and require about 40 hours with four people working around the clock through Christmas. Unfortunatley, due to the incompetence of a secretary the work was lost to another contractor. They used the scheduling and exact procdures I worked out with the processor and completed the task in about 40 hours. It was a very hard and challanging job that this Plumber really wanted to do.
Thanks Plumber and Utah.
As far as the backflow relocation, I've done a number of them on fire lines. My concern is the shut-down and re-start of this particular system. I myself have never seen a "dry system." I'll check with an expert before making a move. I was just kind of interested in how the system works.
Plumber, out here in California, Plumbing and Fire Protection are also seperate trades, as well as seperate contractor license classifications. Few companies perform both anymore.
the dog :cool:
I'd be interested to find why they used a dry pipe system if that is what it is. It cost more to install and maintain and I think it's advanatages are limited in Southern California.
It sounds like the RP would have been a challenging project but rewarding at the same time.
I use to certify and repair devices in High Security prisons here in California. It took for ever to get myself and the truck through the sally port gates.
Once inside, I spent the entire time counting tools and watching over my shoulder. It was the kind of place where unless you brought it with you you'd have to fix it without it.
[ 08-20-2005, 05:09 PM: Message edited by: ToUtahNow ]
The biggest advantage of a dry is system is no freeze worries. This allows the fire sprinkler piping to be installed through unheated areas of a buildingm, a huge consideration in most of the country.
Yeah, the challenge was the biggest reason I wanted to do it. The extra money for working through Christmas was nothing to sneeze at but after a while just having such a challenge is almost enough reward in itself. At least I found out my procedure for doing the job was followed and succesful. Which was a bit of satisfaction.
I did a lot of work inside a hospital for the criminally troubled. Every door locked in front and behind you. They required two men to work together and to have a hospital escort. They counted your tools along with you. I imagine it was much the same when you worked in the prisons.
Its amazing how fast a patient can remove a round tamper proof shower head with out tools. Don't miss that at all.
I never had to work in the same area as the prisoners as they would move them out of the yard before I got in there but they were just on the other side of the fence and liked to talk.
I installed a drinking fountain at a facillity for teenagers who were hooked on drugs. It was the same thing with being a lock down. Somehow they stripped a piece off the new fountain and used it as a screwdriver to take the bars off of the windows.
They were caught before they got out but I heard about it. I explained had the administrator installed the prison fountain I recommend they would not have had a problem. The administrator felt the institutional fountain was too pricey.