What did we do at work today? 14/05/08

[monkey spanners]

Changed a water pump in a fullwood 600 Gallon milk tank. The trick with these is to do the bolts up till they snap, quicker than trying to undo 20yo rusty bolts, needs a 7/16 crowfoot socket and 12" extension bar to get at them :eek: and unscrew the pumphead from the motor and take them out seperatly.
Got new pump fitted and running and then the customer said he had'nt wanted it fitted:( He also insisted on keeping the box the pump came in so no doubt even now he's trying to find out how much it cost so he can moan about my mark up, thats farmers for you :D

Jon

[chillin out]

Today for me...

Drove 3 hours, replaced a relay and cleaned out a drip tray, drove 3 hours home.

Chillin:):)

[TRASH101]

In the middle of replacing 40 filters on in-void units and checking all the addresses then brushing out 90 4 way blow diffusers then updating a database for an asset register then who knows? :confused:

[nike123]

Today, I was on small family hotel "in construction", on which I was from beginning (6 years ago and it is still in construction:eek::eek::eek:) as project manager for my ex. company. Today I was in role of supervising and rectifying mistakes made by untrained and unqualified staff from my past company.
I found about 15 missing isolating valves on hot water preparation and air conditioning distribution room, and about 4 missing safety valves. Also, they did not know how to charge solar water heating plant with antifreeze solution and at what pressure should it be. Then I also found that in project for this plant is missing expansion vessels for hot water tanks even if the non return valve is fitted (by authorized project) and, after my conversation with supervising engineer for whole installations I found that he don't see nothing wrong with that.:eek:
Then I gone to pub to discuss general state of our trade in local community, and found that is better to talk about womens and pets then that, because nobody understand my frustrations!:rolleyes:

Now I thinking to go back to pub and force someone to discuss more about that!:cool:

[TRASH101]

talking of women and pets Nike, my wifes aunties budgie.......

only kidding :D

[chemi-cool]

Replaced two 6 HP condensers and four fans, recovered 26 KG of R22, changed two driers and put the units back to work just in time to cool the milk tank....

Drove 150 KM, stared at a nice sexy behind while having cold beer on the way home.......



Chemi:)

[US Iceman]

...and found that is better to talk about womens and pets then that, because nobody understand my frustrations!:rolleyes:


How can that be any less frustrating than what you are doing on the project?:D

[nike123]

How can that be any less frustrating than what you are doing on the project?:D
I just trying to find frustration that is matched with type of beer in local pub.:D

[Grizzly]

Today for me...

Drove 3 hours, replaced a relay and cleaned out a drip tray, drove 3 hours home.

Chillin:):)

OK Chillin.
I know Scotland is large but just how big an area do you look after?
"4hrs yesterday, 6hrs today" I forget your answer in a previous post...Paid travel I hope?
Grizzly.

[chillin out]

Almost all of it.
I am meant to have a smaller area but I am the only person in the company doing the job that I do, so every other area keeps nicking me...lol
Yep, paid travel.

Chillin:):)

[US Iceman]

I just trying to find frustration that is matched with type of beer in local pub.:D


OK. I thought the source of frustration may have been the barmaid saying NO!

[nike123]

OK. I thought the source of frustration may have been the barmaid saying NO!
With money in my pocket, I newer came upon at such a barmaid! Except, of course, when is closing time.;)

[Chunk]

Changed a shaft seal on a screw compressor,then finished off some jobs left over from yesterday.

Thank god the weathers cooling down.I cant believe that we have so many problems when the temperature gets anywhere near 20*c.

Typical British weather!!!!

[750 Valve]

on the 14th I walked into a whole store iced up on my last day working away from home, I wanted to be on my way home by lunch as I had a 360km drive home but hung around till 4pm getting everything running again, all cases and rooms iced up in a supermarket as a sparky disconnected a wire that fed power to all the defrost relays, needless to say the relays wouldn't pull in and de energise the SORIT valves fitted to all racks which = mass ice ups.

Then drove 360kms to get home, got home at about 9pm after dinner on the way home.

[chillin out]

I have had that happen to me once, the pack defrost controller failed. I used the fire hose next to the cases to defrost them.
Well actually I got the store manager to do it while I "repaired" (sat on my bum) the pack in the plant room...lol

Chillin:):)

[750 Valve]

I have had that happen to me once, the pack defrost controller failed. I used the fire hose next to the cases to defrost them.
Well actually I got the store manager to do it while I "repaired" (sat on my bum) the pack in the plant room...lol

Chillin:):)

store manager on the hose hey.... I'd like to see that, over here they'd laugh at you and just claim a stock loss

we can be up for a fine for using a fire hose over here, usually we have a hot water tap piped under most case line ups, makes it easier with hot water too :cool:

[paul_h]

Didn't do much on the 14th.
Today I looked a a rooftop package a/c that was tripping the c/b
Compressor wiring had shorted under the terminal cover, contactor had welded in.
Could have maybe fixed it, except for the fact that it was a 30 y/o Pope unit. Unit was an "attic" style package unit for those old enough to remember them. To those younger readers, picture in your mind a window mount style RAC wih ducting hanging from the front of it for evap inlet and outlet.
Nothing was left of the chassis, all rusted away. So not much holding the compressor and fan motor in place, the moving fan motor meant a chunk of each blade had been taken out when hitting the cowling.
Miracle worker I may appear to be to the layman, but nothing could save that old Pope!

[monkey spanners]

Hi Paul

I've seen something similair on an old Marstair unit on a factory roof. The compressor was only held by the pipework and the system had finally ground to a hault when the fan blade had bottomed out on the chassis as the motor braket made an escape bid out the bottom of the unit.
The indoor unit was so old the sides of it where made of wood, actual wood:eek:
Customer couldn't believe it wasn't fixable lol

Jon

[Peter_1]

Replaced filter driers of a Bitzer pack 5 compressors for teh 3th time.
Emptied the milk (POE oil with water) out of the compressors for the second time.
All this due to a severe leak on a PHE of 3 years old.
Pictures are from the suction core.
Nice job, isn't it?:rolleyes::mad:

[Peter_1]

BTW, what you see around the core is ice mixed with oil.

[monkey spanners]

Peter, those filters look realy grim :confused:

Jon

[Peter_1]

Disappointing is that my son replaced today again the suction filter and it looked similar to the one on the pictures.

[Grizzly]

Peter.
Have you any Idea as to how the cross contamination is occuring?
Grizzly

[Peter_1]

Client called us because water was leaking out the PHE.

When we came on site, we not only saw water dripping out the PHE but we also heard a sissing sound.

This PHE is mounted on the discharge side of the main discharge line of a pack to preheat water.

High pressure is most of the year around 11 to 13 (160 to 188 psi) bar and assisted with an aircooled condenser, both fans controlled with a VFD and set to 14 bar (200 psi) for R404a.
All compressors have a HP cut out switch, set at 23 bars (333 psi)
Max working pressure of the PHE is 35 bar (507 ps)
Water pressure never goes higher then 4 to 5 bar.

We're a little bit afraid that we don't know the reason for this failure.

The PHE was opened on one side on the front plate.
I've add some pictures taken with my mobile pone when the PHE was in place. I took also some high quality pictures in our shop for the insurance company. Have to resize them first so that I can post those here.

[Peter_1]

Some pictures with the PHE in place when we just made the pack.
The PHE is an AIA from Sweden.

[Peter_1]

Some more. Any help will be greatly appreciated.
You can see that we had at the side of the PHE more leaks then just the one with the bended front plate (bended only on one side)

[The MG Pony]

Poor water quality ate through the Plate HX by the looks of it with possible crystal growth on the inside, they do wonders for rupturing assemblies!

[chiller-man]

Is the water flow rate constant or does it stop and start? if it stops, is the water very hot? maybe the water is expanding so much because the flow rate is very low or even water is standing still inside the heat exchanger (de-superheater) A bit like a pressure cooker!

[yinmorrison]

Hello Peter,

Have you investigated the secondary system on the PHE as it appears to be Galv pipe connections and more than likely this will be the source of the corrosion,or even the possibility that the design of the secondary water system has caused corrosion which has eventually caused particles to be trapped in the PHE causing the burst.

[Peter_1]

Waw , what a quick replies.
To answer some of your questions:
The water flow isn't stopping.
Temperature of the water is never going higher then 50°C, (122°F) discharge temperature never goes higher then +/- 75°C (167°C) We run with a small overall SH and there is a continuous usage of warm water during the day.

On the water tank is a pressure relief valve which opens at 6 bar (87 psi)

The PHE is made of stainless steel. If something should corrode, then I think the galvanized steel will corrode and not the PHE plates. The inox has a higher voltage potential then the steel. Am I seeing this right?

I will make the comment about the galvanized steel to the manufacturer.

The water is water coming from the mains and is drinkable water.
Particles trapped is possible, the residual water was brown but can this burst at a water pressure of +/- 5 bar (70 psi)?

Im' thinking of grinding open the PHE. What do you think?

[yinmorrison]

Galv Steel , Stainless Steel and a direct water supply are a recipe for corrosion Peter and yes it will be the Galvanised pipe causing the problem as it will over 3 years almost certainly have corroded especially at the connection point on the S/S PHE. Has the PHE ever been cleaned out as the manufacturers usually reccommend that this be done.The water ways in a PHE are very small and lend themselves to trapping corrosion material.

[monkey spanners]

Those plate heat exchangers are brazed with copper, maybe the copper has been eaten away.

An engineer at my last company left some milkstone remover (phosphoric acid) in one overnight to remove scale and the next morning we had a nice little fountain:eek:

I have seen platecoolers fail in milk lines due to cracks between plates. According to the milking parlour engineers this is due to the plates flexing when this milk is pumped through, stainless steel has a poor metal fatigue life.

[al]

Hi Peter

Had a condenser PHE on a 500Kw chiller fail, contacted alfa laval to be told this was impossible!! stripped and rebuilt, alfa's concensus was some sort of hydralic lock on the fridge side(possibly involving the oil?)

Al

[US Iceman]

Peter,

I will post some comments in the other thread.

http://www.refrigeration-engineer.com/forums/showthread.php?t=13166