Old Fire detector (Calling all old gits...)

First off all apologies for the **** picture, I only seem to have a picture from ground level which I have cropped, I thought I took a close up as well, but alas, I did not

Anyone recognise this detector, and whether it was supposed to have any kind of cover?

Its a heat decetor, rated at about 160C and made by gent according to the engraving on the side, the black thing in the middle is the bimetallic strip, the fixed end seems to be mounted on a block of paxolin or similar, so I did fear that the strip could be live*, but I tested it, so either its not as I feared, or the system is isolated.

*It appears to be part of a 240v three wire system, as no panel was evident and a closer look at the bells revealed they were rated at 200-250v

The Detector is mounted on a loop in  b/e conduit box, so I'm presumbing its wired in MICC, but didn't go taking it off as didnt want to be disturbing old pyros end of day on a Friday!

I'm guessing it probably dates from the early 1960s as that appears to be when the building was converted to flats.

So, anyone ripped anything like this out?, I won't be as rude to ask if anyone can remember installing anything like this

The old Gents drop head heat detector fitted quite a few of them in times gone by and they were still being installed until the early 80's

What you see is what you got the white cowl was an optional extra and a lot of the heads were fitted without it

If you push the bimetallic strip up you can drop the detector down to reveal the mercury switch

The 240v three wire alarm system was quite common and still in use in a lot of places until the mid 80's it's downside was no battery backup converted a lot of them with the drop front Gents panel that was popular in the 70's

Thanks for the information, it just looked like there was something missing... would you want that thing on your ceiling!

I didn't want to prod about too much and end up setting the bells off, but it looked like the end  bi-metallic strip moving upwards was what happened when it was heated wasn't sure how it opened up.

Interesting to note about the mercury switches inside, I can remember when I was a kid my dad having a couple of them on a shelf in the garage, he worked for a catering equipment manufacturer and they'd be fitted on the arm of the float valve of the water boilers in the 80s, somehow don't think that sort of design would be allowed these days incase it got broken!

Phoenix said:

I didn't want to prod about too much and end up setting the bells off, but it looked like the end  bi-metallic strip moving upwards was what happened when it was heated wasn't sure how it opened up.

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As the bi-metallic moved upwards when heated it unlatched the head which dropped and operated the mercury switch which is why they were called drop head detectors

Lost count of the number of false alarms they caused because of people using matches or lighters on the bi-metallic strip and then claiming they didn't use matches or a lighter despite the telltale signs on the detector housing

As for wanting it on your ceiling there wasn't much choice back then

Yep!  As Ung  says    Gent drop down bi-metalic jobbies ...I only remember them as 24V   but could be wrong , perhaps they were both . 

Gent Rat trap

usually from a stainless steel cuved side Control panel,with an onboard break glass

i think they were spec'd by Barclays

Evans Electric said:

Yep!  As Ung  says    Gent drop down bi-metalic jobbies ...I only remember them as 24V   but could be wrong , perhaps they were both . 

Click to expand...

There were a few types from what I remember of the Gents catalogue of the time I just can't remember exactly what they were and whether they were different for 24v and 240v, There is something in the memory cells has got me thinking they had 2 or 3 operating temperatures but I can't be certain

kerching said:

Gent Rat trap

usually from a stainless steel cuved side Control panel,with an onboard break glass

i think they were spec'd by Barclays

Click to expand...

They were spec'd in a lot of places, probably one of the most used panels in it's day. Used them a lot when converting systems from the 240v systems that had no backup power

Replaced loads of batteries in those panels they took about 20 rechargeable D cells in sticks of 5 clamped into the bottom of the panel

Certainly a trip down memory lane