Air Aspirating Smoke Detection 2

[pipesnpumps]

I need to quickly come up to speed on where and how this technology can be applied, lessons learned, things to look out for, etc.

Specifically, are there any instances where aspirating smoke detection would not be equivalent to or better than photoelectric detectors?

They are being proposed as a value-add option to increase maintainability.


Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[cdafd]

Is this for a spefic application such as clean agent or just general question

 

[pipesnpumps]

This is for general areas, including electrical rooms, instrument rooms, control rooms. Some would be in rooms with clean agent systems, some not. They are proposing this for ease of inspection and maintenance. Thanks

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[stookeyfpe]

In my opinion the use of this form of smoke detection improves the reliability of the fire alarm and detection system. Air aspirating systems can be programmed to be more sensitive to incipient fires and because piping is used to capture combustion products, maintenance is less expensive when compared to area smoke detectors.

 

[b1ueshift]

We use these a lot in Australia in server rooms, prisons, cold storage.

The advantage for server rooms is that there is very early warning as they can detect the pre-ignition products of combustion. For prisons is protection against vandalism, remote maintenance & it avoids having anything electrical in a cell which can be used as a source of ignition. For cold rooms, the system can be remotely maintained and false alarms cannot be triggered by water vapour in the air.

An aspirated system can detect anomolies very quickly. I came accross one in an electrical transformer room once and the maintenance manager said it would register an increase in air borne particles if the transformers were running a little hot (ie if they had a high current draw on that particular day).

The aren't many disadvantages. Someone could tamper with the sensitivity settings of the system down the track. Aspirated systems usually respond quicker to a fire but, they could be slower (at least in theory) if there was rapid ignition as the system has to wait for the air to travel down the pipes and reach the head. In a 4 pipe system, the head will test the pipes one at a time leading to further possible delays as the system could test 3 pipes before testing the one with the smoke. The system doesn't pinpoint the location of the source of smoke like an addressible point detector system can.

 

[pipesnpumps]

Thanks for the responses. I had sort of noodled some of that out, but it is nice to have confirmation, and I was not aware of the 4 pipe being polled situation and some other nuances.

In this instance if they use this detection, I am going to require that the pre-action sprinklers and clean agent require only one detection to start their sequences (pre-action valve, evac timer).

I am comfortable with spot detectors at 0.7xlisted spacing (cross zoned) programmed to require two detects for activation, but two pipes into a single detector head would depend on the timing that it polls each pipe, and how fast it evacuates the clean air within the pipe to draw in smoke. I suppose they could put in multiple detector heads, but that is probably not cost effective.

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[cdafd]

not a air expert or fire protection system expert.

but would sugggest not using one activation to dump a system, especially clean agent!!!!!!!

most recent was either two smoke detectors or one smoke detector and one air

did not think about that the air would not pin point a location, but normally see more then a few seperate air units that cover a certain area of the floor space, so even with a smoke detecor you still have to look in a good size ares for the problem.

yes the air samplers are more sensitive then the smoke detecors, so they will pre alert sooner then the smokes, depending on how they are set up.

 

[DavidCR]

If you look to NFPA 75 and 76 (telecommunications and data centers) there are specific requirements dealing with "very early" and "early" smoke detection and detection to control of clean agent extinguishing systems. As far as I know these are the only mandatory issues on NFPA that makes you consider air aspirating technology.

For other applications, I think it is choice depending on the designer criteria to judge if this technology works for your case.

I've seen a demonstration where they install a VESDA over an air conditioning system of a data center working fine with smoke tests (I doubt that a spot type detector would work as fine on this condition).

The main disadvantage of this technologies is that if you have several independent areas or zones to be protected, it may implicate expensive solutions compared to regular spot type detection systems with addressable devices.

 

[chillylulu]

We install Vesda detectors, and I am manufacture trained in their design. I also took the hands-on tech course. All of these systems require designers and installers to be certified.

1. They are better in most situations, 1 detector can cover up to 20,000 SqFt with a piping network.

2. The maintenance and inspection of these types of detectors is different. Outlets need to be checked and cleaned. The detector can often even measure if the inlet holes are getting blocked.

3. For rooms with electronic equipment, they are great. They can sense very low levels of combustion. Sometimes, you can avoid a fire by taking equipment out of service that is starting to go bad or was improperly installed. This level can be detected and you can be notified. You can set the threshold for trouble, alarm, etc.

4. Many detectors have a program that allows them to measure the baseline levels of the environment over time.

5. Some applications are not suited for this type of detection. For instance, areas with a lot of dust or dirt can clog up the filter or inlet ports quickly.