Subscriber Discussion

Is There A Door Strike With Solenoid Selectable Failsafe/Failsecure?

U
Undisclosed #1
•Dec 27, 2016
IPVMU Certified

If not, would it be useful?

The idea being for use cases where the strike needs to be set for long periods in both locked and unlocked positions.  

Currently if during business hours you wanted the door to be unlatched, but for after hours you wanted it latched, in a failsafe configuratuon, you have to keep current flowing thru the strike for 12 hours at night to keep it latched. And the reverse for fail-secure. Running constant current shortens the life and can make strikes get hot. 

Instead what if you could (somehow) change the strike from failsafe to failsecure electrically, when needed?

Then you could set it to failsafe during the day and failsecure during the night, and therefore use very little power.

of course if you can't have the door failsecure ever, then it wouldn't work.  But maybe if no one is in the building (with intrusion detection) it could work well.

kind of like a fail-same mode.

Avatar
Brian Rhodes
•Dec 28, 2016
IPVMU Certified

Running constant current shortens the life and can make strikes get hot.

This is true, but not all strikes have this issue, especially ones rated for 'continuous duty'. The root cause of the problem is generally mitigated by mechanical design of the strike.  Rather, there is no need to selectively change the behavior of the solenoid.

Inside, strikes are fairly complex devices:

Consider the solenoid (labeled '36' above) has multiple positions to move without the need of constant voltage.  If the solenoid extends the rod 'down' to the first position, the armature mechanically unlocks, even when the solenoid retracts. 

To lock, the solenoid moves the rod 'down' again, bumping the second stage of the armature, this time moving it to the locked position, even when the solenoid retracts.

Depending on the position of the solenoid, it drops the rod slightly (to unlock) when the solenoid falls unenergized, therefore it 'fails safe'.

Other designs are springloaded, some move rods up and down, some reverse the solenoid position in the housing, and so on.  

(1)
U
Undisclosed #1
•Dec 28, 2016
IPVMU Certified
In reply to Brian Rhodes

That's interesting.  If I'm understanding correctly it would be similar (in a very broad way) to the way "privacy" locks work, push in the button and it's locked on its own.  So the solenoid moves the mechanism between multiple non-powered states.

That makes sense.

To be clear though are you saying that most strikes do not require constant current when

  1. latched in failsafe mode
  2. unlatched in failsecure mode

or that most strikes are rated for continuous duty?

MC
Marty Calhoun
•Dec 28, 2016
IPVMU Certified

I have had excellent luck with many of the Rutherford models. I have been using those for over 20 years.

 

Give them a try!

(1)
U
Undisclosed #1
•Dec 28, 2016
IPVMU Certified
In reply to Marty Calhoun

Give them a try!

I will, I really will.

Thanks for the thoughtful reply.

U
Undisclosed #2
•Dec 28, 2016

I have installed hundreds of HES strikes (5000 for cylindrical, 1006 for mortise) over the years that are often set to be unlocked during business hours, and I can't think of a single failure. I am no fan of Von Duprin strikes at all, and Rutherford strikes are (in my experience) terrible, but HES has a number of great options that are absolute tanks.

(2)
UI
Undisclosed Integrator #3
•Dec 28, 2016
In reply to Undisclosed #2

I voted agree already but the HES strikes mentioned above with a Smartpac don't get hot and we have had almost 0 failures in the field. Also while I wouldn't classify them as terrible we have had the Rutherford strikes fail in the field.

Take a look at the Securitron UnLatch. They need ~250mA of current to operate and then only require a minuscule amount of power (40mA) to maintain either locked or unlocked state. I only ever installed two of these and had trouble with both (eventually replaced them) because they are not very forgiving when it comes to the door being out of alignment and also there can't be any pre-load on the strike.

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