comp valve testing

[paulwild]

hi guys
how many conclusive tests are there for comp valve testing and in your opinions what are they and which is the best

cheers

[ismayil59@yahoo]

first letus decide what and wich type of valve we are talking about

[taz24]

hi guys
how many conclusive tests are there for comp valve testing and in your opinions what are they and which is the best

cheers


1 Run the comp with the suction valve front seated and see how deep the comp pulls a vac.

2 After you have achieved the vac shut the comp down and see if the vac changes and then how long the vac holds.

3 After futher thought I amend option 3 to.
In certain circumstances If you are feeling brave you can shut the discharge valve while the comp is running and see just how high the head pressure rises (untill it cuts on hp). This is an extreme method of testing and could possibly lead to very serious mechanical failure of the comp.

1 The deeper the vac the better.
2 The longer the vac lasts the better.
3 the higher the head pressure the better.


taz.

[Toosh]

Hi, Taz says it all

Norm

[ismayil59@yahoo]

Hi Taz is right it is a simple way of cheking valve reeds and the saying also is right

[US Iceman]

1 Run the comp with the suction valve front seated and see how deep the comp pulls a vac.

2 After you have achieved the vac shut the comp down and see if the vac changes and then how long the vac holds.

3 If you are feeling brave you can shut the discharge valve while the comp is running and see just how high the head pressure rises (until it cuts on hp).


I agree with the first two points, but think the third is asking for trouble. This is too tempting for someone to do this and not realize what can happen. The only time the discharge service should be closed is when the compressor is OFF.

[taz24]

I agree with the first two points, but think the third is asking for trouble. This is too tempting for someone to do this and not realize what can happen. The only time the discharge service should be closed is when the compressor is OFF.


I do agree with you and perhaps I should of added some caveats regarding the potential risk involved.
It is not somthing to do lightly and perhaps not somthing to do ever.

Like all things. There is not a simple straight forward solution to all questions, I may have over simplified my answer too much..

Cheers taz.

[Grizzly]

Hi Guys.
Am I missing the point?
Surely
1) Running the comp until the suction and discharge pressures are at or around their normal running pressure.
2) Then isolate the compressor by shutting the suction and discharge valves.
3) Watching the rate at which the discharge pressure drops and equalises with the suction..
Would give a fair indication of the state of the discharge valves and or their seats.

How many of you have rebuilt a set of valves and replaced the head. To on start up shut the compressor back down because the discharge is not loading correctly.
Only to hear the gasses screaming past one or more of the Valves when you shut it down.

Of course there are some other influences that can bugger this test up. A passing oil float valve in the oil seperator or solenoid passing in the oil return line?
Generally speaking though you can hear these lines passing. Or feel a large temperature diff across them.

Also the first thing I look for when I suspect worn discharge valves. Is higher than normal Head Temperatures. The more worn the valve the hotter the head gets!
Spot on with the suction test though!
Cheers Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

[US Iceman]

Taz, I didn't mean to rain on your parade. Part of the problem with this type of open forum is everyone is looking for easy answers. And in trying to provide some quick responses to their query we tend to over-simplify and assume a lot more than I'm sometimes comfortable with.

None of us ever want to hear; Taz said it was OK, when you know full well some cowboy just got his first pair of gauges.;)



Am I missing the point?


Not at all. Your post sums up the process as Taz mentioned in his point #2 (in just a slightly different way).

[thermo prince]

Well said US Iceman, - we must reflet on who is our target audience when we read and reply to some of these posts here.
In the effort to be kind, the seasoned tradesmen & engineers may inadvertantly 'encourage' an inexperienced person to work on equipment he is not totally familiar with, or beyond their current capabilities let's say, leading to personal injury or major equipment damage.
Sometimes you can tell by the nature of the question as to the experience level of the originator.
Teaching frontseating/backseating DSV and SSV over the 'net is a bit 'scary' - in my opinion.

best regards
T-P

[Grizzly]

Guys
I appologise if my post sounds a bit fatuous the answer seemed simple to me. But as you have all stated. It is only simple if you have the training or experiance.
Knowing when to share the collective wealth of experiance is difficult as I have said before.
I rather hope that the fact that people post their questions ( appropriatley worded need only apply).
Shows that they care about doing things correctly and therefore are worthy of a reply at least.
I am new to this forum! I have been sitting on the sidelines for a long time. But since joining have become an active and hopefully usefull?
But I would be happy to take some advise from you more experianced guys in the forum.
As to how to decide how detailed a reply I should give?
Many Thanks Grizzly

[Toosh]

Hi grizzly Just say it as you believe it sometimes a long drawn out answers lose the plot


regards norm

[thermo prince]

Hi Grizzly, sorry if anything I wrote may have caused offence. Your's was a good answer and Paulwild's was a reasonable question. I was not targetting either of you.
So dont be upset and keep on writing pls- I enjoy your posts and you have good solid information to offer us all.

I think we are all on same wavelength in comments above - how to keep it " in the trade" and out of reach of the " B&QBrigade" , " the Texas Toms " - the guys with complete Reader Digest DIY book set of how to be a Carpenter/Plumber/Electrician in a few easy steps !

Like you, I also commented on this previously in the Transport forum.

Do we end up writing disclaimer like
" readers of this post follow advice given here at their own risk etc etc.." at the bottom of our messages I wonder?

best regards,:)
T-P

[paulwild]

thanks for all your replies

paul wild

[paulwild]

many thanks paul wild

[US Iceman]

Grizzly, you are doing fine. My concerns were addressed in my earlier posts and I certainly did not mean to step on any toes (beginner or otherwise).

You can well imagine the novice getting a single bit of hard won experience (from someone who has been in this for a while) condensed into a short reply and then doing something dangerous. I tend to listen in to posts and discussions to see what is going on before jumping into the fray.

It's easy to see how a quick and direct answer can be helpful, but in my opinion we need to slow down just a bit to fully appreciate what the question is really about.

Myself, I prefer the spoon-fed approach. That's how I learned and I think it forces the person to really think about the topic, rather than getting excited about an answer without fully understanding what is "all" involved.

[Grizzly]

thermo prince & US Iceman.
No offence taken Guys. Just confused as to what to say and not to say sometimes. Thanks for the input though!
"Spoonfed" I like Iceman.
Not so sure about "Texas Toms" though Thermo Prince. Not a term I have heard before?
But your nice comments about my posts are appreciated!
Got to go, got to sort more "wheat from chaf"
http://www.refrigeration-engineer.com/forums/images/icons/icon7.gif Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

[hendry]

Dear Paulwild,

I believe you are seeking better method/s than the above.

I only recommend valve tests with compresor running when other means are not immediately obtainable.

we do valve test in our workshop on proper piping skid with accurate pressure gage and dry nitrogen.

some methods mentioned by others could be the trial and error way from past.

we think you shoudl carefully study your system on its suitability to perform such acts.

bear in mind, some contractor do not even perform pressure tests prior to commissioning of plant. So if you take over from such people, with the suggestions from others, you will find yourself in deeper sand bunker.

write to me directly if you think our advice/s is nearer to your needs.

[thermo prince]

Hi again Grizzly, good to see you posting away on many topics.

As I remember, 'Texas Tom' was the 'average Joe d.i.y ' character in the tv ad of Texas Home Care centres back in the early 90's.

regards
T-P