automation project blow down

[garfields]

I am an electrician and not a programmer. (read 0 experience) I did buy the book offered from this site over a year ago and i'm sad to say it is still collecting dust. This is for a car wash and will be a system to keep the wands from freezing. I have an existing temperature sensor that will close at 35 degrees to activate the

system.

1. contact close (blow compressed air with solenoid valve for 20 seconds)
2. wait 10 seconds and blow 10 more seconds
3. contact close (open solenoid valve to pump windshield washer fluid in for 20 seconds)
system would now be in standby until the next customer uses it (there is a 24 volt ac electrical signal that closes the motor starter to the pumps so this would be the start of a new blow down sequence after a delay of a few minutes after the customer is done using the bay.)

then same logic repeated for bays 2,3,4,5,6

When the temperature first drops to 35 for 10 minutes they would need to separately and in sequence operate automatically. After that if a bay was used it would go through the sequence by itself.

Looks like I would need 12 outputs and 6 inputs for the 6 bays then I would like a "master solenoid valve" ahead of both the air and antifreeze solenoid valves that open with each sequence so that in case of a stuck open solenoid valve I would have redundancy. I was looking at ezautomation.net and it looks like this plc would do the job. I am looking to pay someone to write this program. It needs to be written with free software and or equipment that I can get into and modify later. If you are a contributing member of this site and I can see that by looking at your past posts I would be glad to pay in advance. Thanks for reading.

 

[flash053069]

There is a couple of questions that need clarifying.

1. The 6 inputs you are referring to are the 24 vac main pump solenoids(1 each for the 6 different bays) correct? If so - is there an auxiliary set of contacts on the 24vac motor starter for a 120V signal
2. Does each bay have it's own separate antifreeze pump or will it be just 1 pump?


At minimum you will need 7 inputs(1 for "Low Temp" and 6 for "Bay in use") and 12 outputs(6 air, and 6 anitfreeze) solenoids.

It is never a good idea to power an air or water solenoid straight from the PLC outputs. You sometimes can get a high voltage dc feedback destroying the output. I would recommend using six 11 pin Ice cube relays 120vac (3 sets of contacts) for the antifreeze solenoids. The antifreeze pump can be energized off of each bays solenoid valve relays 2nd set of contacts paralleled and the antifreeze master solenoid can be paralleled with the 3rd set of contacts). The 6 air solenoids can be 8 pin Ice cube relays(2 sets of contacts) to fire the air solenoid off of 1st set of contacts and the 2nd set can be paralleled to fire the Master air solenoid.

AB's Micrologix 1000 32AWA(20 inputs, 12 ouputs) plc would do the trick. It can be programmed with RSLOGIX micro starter lite and RSLINK lite. Both which are free from their website. You will also need a PM02 cable to communicate to the plc.

The programming will be simple enough if you choose this route. Since this forum is focused on people learning to program PLC's then you could get a ton of advice and kill two birds with one stone(Get your program done and learn plc programming).

 

[osmanmom]

i believe our member fellow can program this system for you but he can't travel why not contact he and discuss.

hope he read this post

 

[Caveman]

We use the ST-1500 guns that weep when not used
to prevent freezing.

 

[garfields]

There is a couple of questions that need clarifying.

1. The 6 inputs you are referring to are the 24 vac main pump solenoids(1 each for the 6 different bays) correct? If so - is there an auxiliary set of contacts on the 24vac motor starter for a 120V signal

(Yes, I'm referring to the coils on those iec motor starters. I could get an extra auxiliary for them)

2. Does each bay have it's own separate antifreeze pump or will it be just 1 pump?

(I plan to use just one air operated flowjet pump.)


At minimum you will need 7 inputs(1 for "Low Temp" and 6 for "Bay in use") and 12 outputs(6 air, and 6 antifreeze) solenoids.

(I think you're right, now that I'm thinking. It would be ideal to have an output for the pump solenoid valve)

It is never a good idea to power an air or water solenoid straight from the PLC outputs.

You sometimes can get a high voltage dc feedback destroying the output.

(These would switch at most 500-1000 times a year. Considering the ratings in the many millions of most contacts I have seen specs on I am willing to take a calculated risk.)

I would recommend using six 11 pin Ice cube relays 120vac (3 sets of contacts) for the antifreeze solenoids. The antifreeze pump can be energized off of each bays solenoid valve relays 2nd set of contacts paralleled and the antifreeze master solenoid can be paralleled with the 3rd set of contacts). The 6 air solenoids can be 8 pin Ice cube relays(2 sets of contacts) to fire the air solenoid off of 1st set of contacts and the 2nd set can be paralleled to fire the Master air solenoid.

(While all of this looks like it would work perfectly It seems to me like I'm losing one of the benefits of the plc by using a dozen relays and changing to 120 volt on everything. With an additional output couldn't the logic just say that the output for the master solenoid valve is on simultaneously with any bay solenoid on?)

AB's Micrologix 1000 32AWA(20 inputs, 12 ouputs) plc would do the trick. It can be programmed with RSLOGIX micro starter lite and RSLINK lite. Both which are free from their website. You will also need a PM02 cable to communicate to the plc.

The programming will be simple enough if you choose this route. Since this forum is focused on people learning to program PLC's then you could get a ton of advice and kill two birds with one stone(Get your program done and learn plc programming).

I have read on the site and other than not understanding the programming it's very intriguing. When I get into the inputs, outputs, different timers, software and on and on it is pretty intimidating. While I was looking at the ezplc line maybe I should go with the Allen Bradley and be more likely to learn here if that's what you guys prefer. Thanks

 

[garfields]

We use the ST-1500 guns that weep when not used
to prevent freezing.

Our water is over 2 cents per gallon which is $1 to $3 per hour weeping to drain depending on how cold it is. I'm hoping this will work!

 

[Sherlock4me]

Is that the way car washes handle those issues? I have no idea.

My background is in Municipal Pump Controls so my humble 2 cents may be worth actually less than that.

What happens when a plc issue requires comms and debugging if you do pay for a program? If you do it yourself with help from here, a badly timed debugging requirement or may be a serious challenge and an unneeded warranty headache?
Or a pipe bursts due to the warming system failing for any number of issues; wand is left on the ground by careless person, foreign matter rammed in air blower by some vandal, fan fails or motor fails on air blower, power fail....
Yes, shutting and draining the lines will take care of that in the short haul, but


1) Weeping nozzles sound so smart with my limited knowledge. I can say a small water filtration plant, (2mgd) ordered the local car wash closed in occasional lean water winter seasons due to weeping nozzles. Maybe 2 or 3 years in the 15 years I services them. So IF weeping nozzles are an economic burden: then...


Disclaimer: This idea is just a humble thought.


2) Is there a last shut off solenoid for each bay's discharge line, (that feeds the line to the nozzles) heading out of the control room? If so, call it Valve_1 for this idea and could a person mount 1 master t-stat, and have that feed a bypass solenoid plumbed in as a short bypass line around each last aforementioned Valve_ 1? (To be clear this bypass, normally open, solenoid valve would only de-energize when temps reached below 35 or if power failed.
Each bypass line would tee off just before and tee back in just after it's respective valve1 in the control room, a foot or so of length (6 bays, 6 very short bypass lines inside the control room) That way, when the bays were in use, the water and soapy mix would flow parallel through the bypass line, no problem there and when temps were above 35 the bypass would be closed and not affect the system. The total would be 6 solenoids, one for each bay, 2 tees per line and a few fittings, a small control box, flex, and two-11 pin interposing ice cube relays, (6 sets of contacts, 1 for each solenoid) and a back panel and a few misc. items...(all system voltage coils on relays and solenoids).


I guess the weeping nozzles could be clogged by a vandal as well the air blowers. But if weeping nozzles do work and are power fail and system fail and breaker trip and left laying on the ground, and program glitch proof why not use them...

Lastly, if it's been bid and engineered, I've seen plenty of times where, once an engineer designs a system that uses a rifle to kill a fly, he is open to a fly swatter once shown one.

I will be interested in what you end up doing as I know nothing about car washes.


Most sincere good luck and I have no valuable advice besides a humble recommendation that you dust off the PLC programming book you bought here last year... : )

 

[Sherlock4me]

I began writing the above before I read the water cost you mentioned. Good Luck Garfields

 

[garfields]

The normal way to protect from freezing is to install a high pressure check valve after the pump then after that a line connected to city pressure and controlled by a normally open solenoid valve. (normally open in the event of a power failure it runs water to prevent freezing lines). This valve is controlled by a % on controller that runs so many seconds per minute and varies based on how cold it is. Ironically, when it's the coldest it runs water continuously and that's when there is no business! If the system doesn't work as I had hoped it really is "learning the hard way," Basically it will cost 0-$50 in parts plus an hour to unthaw and lets not forget the blow to my pride!

 

[jrwb4gbm]

I'm still trying to figure out which PLC platform you are going to use. The Micrologix 1000 or 1100 has free software. There is also a free emulate program you can use to test the Micrologix plc program. Thelearningpit.com has a great training program/plc simulator that is very similar to the Micrologix programming. The Click PLC by AutomationDirect also has free software. Click has some expansion modules capable of 7 amp loads for direct connections but my thinking would be to protect the plc modules with external relays as mentioned earlier. There are also other platforms available with free software. Once the platform is determined, maybe I or others can offer some example programming.

 

[garfields]

I'm still trying to figure out which PLC platform you are going to use. The Micrologix 1000 or 1100 has free software. There is also a free emulate program you can use to test the Micrologix plc program. Thelearningpit.com has a great training program/plc simulator that is very similar to the Micrologix programming. The Click PLC by AutomationDirect also has free software. Click has some expansion modules capable of 7 amp loads for direct connections but my thinking would be to protect the plc modules with external relays as mentioned earlier. There are also other platforms available with free software. Once the platform is determined, maybe I or others can offer some example programming.

I'll just use the micrologix because it's been mentioned the most so questions will probably be easier to answer. What parts do I need? Maybe I should work on the program first then order the parts?

 

[Bullzi]

I would start by making a list of all the I/O you will need for the project. From there you will have a good idea on the PLC you will need.

Attached is a Excel Spreadsheet that I use to get all my I/O down. It may help you out too.

You will also want to download the RsLogix 500 Micro (Free Version) from the Rockwell Web Site. Make sure you get the version with RsLinks Classic included.

 

[flash053069]

I'll just use the micrologix because it's been mentioned the most so questions will probably be easier to answer. What parts do I need? Maybe I should work on the program first then order the parts?

I made the program today. I can email it to you. I would like to post it on here. But, for some reason I cannot upload .rss atachments.

 

[garfields]

I made the program today. I can email it to you. I would like to post it on here. But, for some reason I cannot upload .rss atachments.

Thank you for that. See your pm. That being said I am still interested in following through and writing and or modifying this program. I have other projects this knowledge may help on.

 

[Bullzi]

You have to zip all programs before you can post it here. This is a forum rule. So just select the file and right click, select Send To, then select Compressed Folder. That will create a zip folder right next to your original file.