Regulators protected from unauthorized adjustment 1

[MedicineEng]

Der All:
Does anyone knows any manufacturer of compressed air regulator that can be protected from unauthorized adjustment?
My problem is that I want to reduce the pressure in the use of some open blowing points of my compressed air network as a energy saving measure.
But as already happened in the past, when I install a new regulator in a new point, after some time, the pressure was already increased by the users. As always, nobody did that adjustment, so I believe that the regulators are adjusted by "miracle". To avoid these "miracles" I wanted to change these normal pressure regulators to some that might be more difficult to after adjustment by my staff could be locked to avoid this happening.

Thanks a lot for your help.
PR

 

[Montemayor]

PauloRibeiro:

I don't know where your plant is located or what plant role you undertake, but every plant I've operated, started up, or worked in has a universal standing rule: In the daily operation of a process plant, the Operations Department rules - and that makes the Production Manager king of the hill within the operating plant. His operators, more often than not, usually have a "carte blanche" to operate the units in only one, safe way: the manner that it makes more product, using less raw material and labor. To fulfill this mandate, the unit operators pretty well have their way on how the plant runs on their shift and how the instruments are set (or re-set). The is only fair, and really is the democratic way to operate a unit. If the operators have the responsibility for the operation, they should have the last word on how it is operated.

If you happen to be a plant project, or process engineer servicing the operations department, you're pretty much at their command and you really can't control what they do - or don't do. Unless you are in charge of operations, you really should stay out of any decisions on how the instrumentation in a unit is set or calibrated. However, if you happen to be a production supervisory engineer, then you pretty well should have your operators under your wing and, consequently, under your control. I assume you've got some pretty good operators - otherwise you would have gotten rid of them. That being the case, there is no need to "lock them out" of being able to adjust instrumentation to a particular setting that they find more conducive to delivering you the results that you want: more production with less costs.

Unless your plant operates opposite of what I've described, I don't see any problems. Perhaps you haven't told us everything regarding basic data. Is what I've described pretty much the organizational characteristics of your plant? If not, what is your function and what are you trying to achieve that operations people won't let you do what you want? Operations personnel are the "owners" of the unit and if somebody outside that department is caught re-setting or changing instrumentation signals (including processs engineers), they usually kick butt all the way to the plant manager's office! And you will practically always find that the plant manager will back the Operations Manager 100% - regardless of whether anyone outside the Operations Department changes a setting in an attempt to "help" operations. Isn't that your experience as well?

The above is what I've found in just about every plant - except the ones that I managed. As Plant Manager I loved to fiddle and fidget with instrumentation to "experiment" and witness results. But I had total economic responsibility for the unit. My point is that other than plant managers, you've got a situation where you don't want to handcuff operators to operate a unit other than in the manner that they are accustomed to do so - as long as it is safe for them, for others, and they deliver the results. That being the case, then you'll hardly find a situation where process instruments are allowed to be "locked out". Some are; in fact, I've designed some for that purpose - but these were special situations that involved plant safety and/or experimental runs that were 100% supervised by shift process engineers. These are rare cases.

Could you explain your situation in more detail?

Art Montemayor
Spring, TX

 

[MedicineEng]

Montemayor:
May be you didn't understand which are the points that I want to "lock". I don't want to reset any instrumentation or machine settings. This will be for another occasion and always with the Production management involved.
The points that I want to lock in a determinate pressure are the open blowing points, that is, the points that are usually connected to a hose or a blowing gun and that are mainly for cleaning or drying equipment. I have the compressed air network at around 6 bar, and I wanted to reduce these points up to 2 bars max. This has two reasons:
1-Safety- I still didn't manage to pass the message to everybody that at 6 bar, if a small particle of metal releases from the pipe it might get into the skin of an operator even without his notice;
2-Energy saving- The open blowing points without reduction provoke an extra working and demand on the air compressor.

My experience with one point where I have one pressure regulator is that if I set the pressure at 2 bar, after one week or two the pressure is for shure increased. And if I ask, nobody knows how that happen. So, I remain with the doubt if the persons really need higher pressure in that point (and if it is the case I would need to revise the setting) or if it is by a bad habit.

And that is what I want to avoid.

 

[CRG]

If I were using a typical blowing gun attached by a 3/8" hose, I would not want 2 bars. For cleaning and drying, that is not enough pressure to dislodge debris on many items. In fact, I would prefer 8 bars.

 

[hacksaw]

Following Art M.'s perspective, you need to be very cognizant of the actual operating needs, before you start locking done regulator settings. It is not something easily understood until you don an operators helmet for a week or so. You'll soon discover the idiocy of desk engineering, and cost saving measures that look absolutely convincing on paper and in the meeting rooms, but do not work on the floor.

 

[jmw]

I think the big question needs to be "why?" Why do the operators change the settings? Maybe there is something that they know and you don't. It is important to establish this.

Consultation is a vital part of the success of any operation. It would be nice to say "Do it my way", and, right or wrong, everyone does it your way but the real world isn't like that. This may seem a trivial thing to you as what you are doing doesn't affect their operations. You may be right. It may be that you need to talk with them, explain what you are trying to do and why and ask for contributions. It may be that once consulted and once they understand the situation or even if they are consulted and have nothing to add that they will be content to leave the settings as you have set them.... without the need for a locking device.

Having said that I've been on refinery process plants where the operators always made their own settings and it was not unusual for each shift, as it came on, to change the settings to suit themselves. A big problem for the process manager who was trying for process improvements. You may find that whatever you try and however big a lock you fit, someone will manage to by-pass your precations.

Logic, good engineering or common sense often have no place in such situations and man management does.

 

[Montemayor]

jmw has expressed in an articulate and concise manner what I obviously failed to convey to Paulo. The essential need for accurate and direct communications is of prime importance.

I believe this subject is a practical one that goes to the heart of every real-life operation in the engineering world we live in. It's very important to establish the importance of communicating and identifying the positive need for the various disciplines in engineering. We all contribute to the final success; what often goes by without recognition is the important work that some people add to a safe, economic, and efficient operation. The recognition, of itself, is not that important; what really matters is the realization of all the benefits that can be derived when advantage and use is made of the potential talents available.

Many, many times Operators don't do things in a better and more efficient manner because they simply don't know or they have not understood what is being asked of them.

This subject is so important! It goes to the heart of the entire engineering matter in real life. We, as degreed engineers seldom, if ever, are called upon to do the work. Rather, we are called to supervise, instruct, and lead those that are expected to do the work. Carrying out our basic scope, then, involves a lot more than just calculating and "designing". It takes a lot of correct and efficient communicating - oral and written.

Art Montemayor
Spring, TX

 

[hacksaw]

When the process and its controls are effectively integrqated, and the process is operable, operations doesn't really have a need to redefine how the process should work.

Communications are essential

 

[quark]

I dare to disagree with you guys on this subject. Engineers who are well versed with their subject (like you guys) can maintain the things in a better way. But as far as my experience and observation is concerned, compressed air is grossly overlooked and always thought as a free resource. Pharma Industry is a main cuprit for this.

Unfortunately people think that the minimum pressure required by their processes is the restart pressure of the compressor. But when I did continuous monitoring of the pressure pattern, the air pressure at the equipment was much lower sometimes and nobody noticed nor complained. The ConservAir(see

http://www.conservair.com)

people use the same trick and try to provide continuous supply at this low pressure so that the process is optimized.

Before submitting myself to their knowledge, I did one year survey at various plants(including Pharma, Automobile, steel and Chemical sectors) where they did similar sort of jobs. I observed some instances where the increased pressure was offset by increased leakage and at the end the pressure was same. This might be due to gross negligence of the plant engineer, but I am aware about the difficulties of maintaining a plant with minimized leaks.

Paulo Ribeiro

My suggestions will be

1. To check the actual pressure required by the process and required flow rate.

2. Correct pipe sizing

3. Correct receiver sizing

4. Minimizing leaks

Once you are done with this exercise you can get confidence.

As far as regulators are concerned, why can't you put a pipe sleeve around the stem of the regulator so that the pressure can't be varied without removing the sleeve?

Regards,




Eng-Tips.com : Solving your problems before you get them.

 

[saxon]

Paulo, So you've got "gremlins" adjusting manually set valves from one shift to the other. Sounds like operations is fine tuning the process to its actual needs. Have you ever thought of using restriction orifices to accomplish the pressure drop?. Nothing to operate, except to dissassemble the line and remove the orifices.

Hope this helps.
saxon

 

[abeltio]

Paulo Ribeiro,
Had a similar same problem with the speed control of an emergency diesel generator... each good samaritan, they honestly tried to help, on site thought that he/she would fix the operation of the emergency diesel by "tweaking" the speed regulator... the only thing achieved was a lot of grief and a diesel genset that was completely out of whack...

there is no substitute for all the good advise given by the postings above... all of them make absolutely perfect sense... but you still have no "option"...

What we did with the genset was... we built a box that prevented access to the speed control card locked with those multiple padlock locks... one from operation one from maintenance.

This satisfied everybody... once calibrated and tested no one could modify the setting without the other party knowing of it.

In your case, changing all the regulators for a lockable type may be very expensive... building a box around each regulator with the multi-lock system could be advantageous... both in $$$ and politically with the Ops people...

HTH


saludos.
a.