Door controls

[ecclesk]

With the increasing electricity costs we are looking at all options available to reduce consumption.

I am currently trialling a new door control system for one of our coldstores.

It’s an automatic sliding door, the original control consisted of a pull cord inside and out, and a timer which would close the door after say 15 seconds.

On the closing edge of the door was a rubber safety edge which if impacted when closing would re-open the door. The problem was these rubber safety edges are easily damaged and we could not shorten the 15 second timer as this door is mainly used for pedestrian access but they also bring order picking cages in & out which requires the timer being 15 seconds to prevent closing on them.

I have built a new system using a small PLC and 2 photo electric switches, one just of the floor and one around waist height(see pictures), these produce two sensing beams across the door way and these replace the safety edge an monitor activity in the door way, basically you pull the cord the door opens, a forklift or person passes and breaks the beams, upon the beam re-making a timer closes the door behind you after a 3 second delay. With the old system the door would be open for 15 second even if the doorway had been clear for 10 of those hence being open unnecessarily.

The beams also prevent the door from closing if there is activity in the doorway.

The problem we had at first was the reflectors on the closing edge of the door were prone to condensation which would break the beams, we have overcome this by installing a small shroud around the reflector and a heater pad on the back.

I now have a similar problem with the cold mist coming out of the store breaking the beams, we have strip curtains in place which are in good condition, this only seems to happen now and again depending on ambient temps & humidity I think.

if i could install this system on the rest of the doors on site i think it would reduce the amount of door open time greatly, but untill i have a trouble free system i cant.

does any one have any ideas on how to overcome the mist problem? i am considering fitting different (more powerfull) sensors but they are expensive.

[Paulajayne]

Hi

1. Turn up the sensitivity on the RX units until the condensate no longer breaks the beam.
2. Fit higher intensity TX units and adjust as the RX units to suit.

The more powerful TX units can be cost justified on the saving made.

Paula

[ecclesk]

Thanks for the reply.


1. Turn up the sensitivity on the RX units until the condensate no longer breaks the beam.

On the model i am using there is no sensitivity adjustment.


2. Fit higher intensity TX units and adjust as the RX units to suit.

I am currently looking at different models, the ones i am using have a range of 4M (door opening is 2.5 - 3M) i am thinking about using one with a 10M range as i would have thought it must have a more intense beam.

I am pretty much on my own working on this so welcome any thoughts or ideas.

I did also think about using an induction loop but the cost & installation has put me off.

[Peter_1]

You can use ultrasonic for this because this sensing device isn't disturbed by the mist.
Assemtech UPX500 PVPS 24
Honeywell 944-T4V-2D-1C1-130E
Pepperl+Fuchs UB2000-30GM-E5-V15

Look also once to the Omron E3Z-LS range

Look also once on the site of www.sensopart.de
They have laser sensors in the range of 300 €

Another concern, what happens if the door closes and on the ame moment, the supply of your transmitters is failing on that moment or just the IR transmitter (the beam) brakes?
I think your door will close anyhow.

For safety reasons, at least in Belgium, you have to install a fail safe PLC.
And the rubber safety edge isn't that abd: if it's broken, then replace it because it's rather cheap.

The system is installed insise the coldstore?
Is it a coldstore or a freezer?

[ecclesk]

Another concern, what happens if the door closes and on the ame moment, the supply of your transmitters is failing on that moment or just the IR transmitter (the beam) brakes?
I think your door will close anyhow.

the sensors are n/c wired so that if they fail the door opens and stays open.


For safety reasons, at least in Belgium, you have to install a fail safe PLC.
And the rubber safety edge isn't that abd: if it's broken, then replace it because it's rather cheap.

the system is using a PLC.

i know the safety edge isn't that bad, but the idea with this system is to close the door behind you so it's open no longer than needed (energy saving), as the old system was timed for 15 seconds but a lot of the time, if it was just a person without a picking cage they only need a few seconds so the door when be open longer than needed, we could not shorten the time as the door is also used for people bringing cages in and out which takes longer.


You can use ultrasonic for this because this sensing device isn't disturbed by the mist.
Assemtech UPX500 PVPS 24
Honeywell 944-T4V-2D-1C1-130E
Pepperl+Fuchs UB2000-30GM-E5-V15

Look also once to the Omron E3Z-LS range

sound like thats just what i'm looking for!

i'm currently using the omron E3JM model

i will look into this and keep you updated.

Thanks for the advice