# Fire trucks and plcs



## denny3992 (Jul 12, 2010)

denny3992 said:


> Was at a fire truck show and saw a demo truck with 4-hmis o control everything on truck from 4 corners of body... Asked salesman bout what kinda software and plc... Got a
> Blank stare! Call me old school but ill take a manual valve over a solenoid fir firetrucks anyday!


Any cant imagine how they keep it from getting wet?


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## Big John (May 23, 2010)

It's the name of the game, now. I know some guys that did a protection and controls upgrade on an HVDC converter station, they said it was the first in the world that did not have switches. All HMIs and ethernet connections. But not a single damn electromechanical switch or button to push in the whole substation.

I think there's a risk of making things overly complicated, especially when reliability is paramount. My argument when doing PLC upgrades was I still wanted the option for 100% manual control: If something goes to hell in the electronics or programming, I want to still be able to operate this thing. Unfortunately, that's just not how stuff is designed. Even "manual" control of most processes still goes to inputs on the PLC.


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## LGLS (Nov 10, 2007)

Darn, it's almost like they took all the knobs and dials and switches off the TVs!


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## MDShunk (Jan 7, 2007)

I'm somewhat familiar with the HMI's on emergency equipment, and they're not really connected to PLC's. They are most often CANbus connected to an industrial PC running Linux.


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## Jack Legg (Mar 12, 2014)

MDShunk said:


> I'm somewhat familiar with the HMI's on emergency equipment, and they're not really connected to PLC's. They are most often CANbus connected to an industrial PC running Linux.


wow:blink::blink:this place makes me feel so stoopid some times:laughing::laughing:


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## JRaef (Mar 23, 2009)

denny3992 said:


> Was at a fire truck show and saw a demo truck with 4-hmis o control everything on truck from 4 corners of body... Asked salesman bout what kinda software and plc... Got a
> Blank stare! Call me old school but ill take a manual valve over a solenoid fir firetrucks anyday!


I think the concept is that the valves can be controlled from wherever you are on the truck. In the manual version if the truck side that has the manual valves is obstructed, they can't control it. So the drivers have to be careful in tight spaces, which might mean not getting the truck close enough to the fire or water source.


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## don_resqcapt19 (Jul 18, 2010)

denny3992 said:


> Was at a fire truck show and saw a demo truck with 4-hmis o control everything on truck from 4 corners of body... Asked salesman bout what kinda software and plc... Got a
> Blank stare! Call me old school but ill take a manual valve over a solenoid fir firetrucks anyday!


Yea, but the engineer doesn't have to know his hydraulic calculations...you just set the GPM you want out of each port and the computer does the rest

I don't know if they still teach it now, but 30+ years ago, if you wanted to be an engineer on the Chicago Fire Department, you had to do all of the hydraulic calculations for friction loss and flow rates in your head. They would throw in things like different hose lengths, elevation changes and nozzle types.


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## erics37 (May 7, 2009)

I've worked on a bunch of pump stations that got updated with 100% PLC control. It works great, when it works, but if the PLC spazzes out then they're screwed until it's fixed.

I remember getting a wastewater pump station running a couple years ago with some standard residential septic tank floats taped to a stick of PVC hung from a piece of strut straddling the manhole, temp wired with a piece of romex to the "Jog" input terminal on the VFD. Really ghetto.

I'm all for PLC controls but for critical infrastructure I think it's paramount to have manual backup control. At the very least, some high/low floats with relays to make the sh!t move.

Same deal with PLC fire trucks. If my fire district tried to buy one of those I think the taxpayers would revolt :laughing:


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## qckrun (May 18, 2009)

I'm currently Rewiring a 30+ year old part of the Wastewater Treatment plant I work at. Our head boss wanted everything on the PLC, no HOAs or anything, all controlled on the HMI. I asked him, so when the Plc decides to quit, which happens often due to the IT dept screw ups, how will you run the pumps that run non stop. He gave me a blank stare and said I dunno, I guess we do need the HOAs. 

I think it's awesome to have a PLC to control everything. However PLCs and computers fail ALL the time. If it's a critical piece of equipment or area, I think you should always have the functionality to run in Hand or Auto, and have the system work in it's intended purpose in both modes.


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## glen1971 (Oct 10, 2012)

qckrun said:


> I'm currently Rewiring a 30+ year old part of the Wastewater Treatment plant I work at. Our head boss wanted everything on the PLC, no HOAs or anything, all controlled on the HMI. I asked him, so when the Plc decides to quit, which happens often due to the IT dept screw ups, how will you run the pumps that run non stop. He gave me a blank stare and said I dunno, I guess we do need the HOAs.
> 
> I think it's awesome to have a PLC to control everything. However PLCs and computers fail ALL the time. If it's a critical piece of equipment or area, I think you should always have the functionality to run in Hand or Auto, and have the system work in it's intended purpose in both modes.


True, except some controls have a relay upstream of the Hand, controlled by the PLC, so that the equipment won't run in certain conditions. Such as an exhaust fan in the event of a fire or vibration shutdowns on pumps or fans...

Some places also use spring return switches for Hand, so that they can't be left in Hand without an operator being there..


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## qckrun (May 18, 2009)

glen1971 said:


> True, except some controls have a relay upstream of the Hand, controlled by the PLC, so that the equipment won't run in certain conditions. Such as an exhaust fan in the event of a fire or vibration shutdowns on pumps or fans... Some places also use spring return switches for Hand, so that they can't be left in Hand without an operator being there..


I realize that, I was commenting on when people do not want any HOAs in the process of the equipment. I know you can wire it up to bypass the Plc in the event something happens, but when it's 2am and no one is there and you need the equipment ASAP, I believe you should always have an HOA. 

I know a lot of HOAs have different setups, to prevent starting up in hand when in auto mode. Currently I'm wiring HOAs in this state, that when in hand you cannot start the motor in auto and vise versus.


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