Urednici: goranfri,nike,sim,Honorarac
Uman čovjek!Soko je napisao:@goranfri: Auuu, veci si manipulator od Picoustog.
Nije pretplata nego taksa, jeli?
Pull down - svaki kompresor bi to trebao valjda preživiti!@nike: mozda je na vrhu radnog opsega kada postigne +4C ili se priblizi. Sta cemo do tada?
Kažem ti, drž vodu dok garancija prođe. Inaće nema profita!LBP kompresore stavljaju jer su 20-30% jeftiniji od MBP/HBP kompresora iste radne zapremine.
Klasika za talijane i ostalu bandu sa ovih prostora koja ih kopira.
Ne znam ima li dovoljno mjesta u avionu za gajbu ispod sica! Bude li, obećajem svećano (časna Titova pionirska) da če bar pola gajbe stići na odredište!goranfri je napisao:
Pivo uvek može a Ožujsko obavezno stavi ispod sedišta par flaša da ne kuka više ovaj Soko , i da ga mine želja
. 
The capillary tube is a very popular metering device used on many fractional horsepower refrigeration systems. It is basically a length of very small diameter copper tubing soldered or brazed between the system’s liquid line and the inlet to the evaporator. A common problem encountered with this metering device is that it can become restricted, causing a reduced amount of refrigerant to flow into the evaporator. Although a capillary tube can become totally restricted, a far more common problem is when it becomes partially restricted, allowing some refrigerant to flow into the evaporator but not enough to satisfy the requirements of the system.
This seemingly easy problem to diagnose is actually rather tricky at times. This is because a restricted capillary can resemble a system with a low refrigerant charge. Both problems can present similar symptoms. A system with a restricted capillary tube will operate with a lower than normal suction pressure, as will a system with a low refrigerant charge. Both system problems will also operate with a lower than normal discharge pressure. Depending on the severity of either problem, the pressures may not be exactly equal, but close enough to cause any technician difficulty in determining the true problem.
This may lead a technician to guess at the problem and tell the customer that the system has low refrigerant charge due to a system leak - a reasonable conclusion. The customer okays the technician to search for the leak, repair it, and recharge the system with refrigerant. After much wasted time, the technician is unable to find the leak and tells the customer that the leak must be so small that he cannot locate it. It is best to just go ahead and recharge the system with some refrigerant and see how long it takes to leak out - again a somewhat reasonable conclusion.
As the technician adds refrigerant to the system, he notices the low side pressure does not change much, but the high side pressure starts to climb well above normal levels. He realizes the problem is not a system leak as he first suspected, but a restricted capillary tube. Now he is faced with telling the customer that his original diagnosis was incorrect and that now the system has a more serious and more expensive repair. This leads to a very unhappy customer and an embarrassed technician.
Since most capillary tube systems have a relatively small refrigerant charge, one practical approach to determining the difference is to remove the refrigerant charge and weigh in the correct amount of refrigerant. If this resolves the problem, the issue was a low refrigerant charge more than likely due to a system leak. Now it makes sense to go ahead and spend the time to search for the system leak. If the problem remains after adding the correct amount of refrigerant, the problem is most likely a restricted capillary tube.
This method is a little time-consuming, but it will allow a technician to diagnose the true cause of the problem the first time without guessing and potentially misinforming the customer.
Although the service problems of the cap tube
itself are simple, it’s the entire system that more than
often leads to complications that involve the customer,
serviceman, service manager, the owner of the company,
the factory sales manager, the president of the factory,
even the better business bureau finds itself involved. The
many hours of aggravation on the phone and the threats
of attorneys by mail usually starts with what is seemingly
a very minor service call: the evaporator is not fully
frosted. All texts and service manuals describe this as a
very simple problem and I quote “the undercharged
evaporator can be caused by a slight shortage of
refrigerant in the system or a slight restriction in the cap
tube”. That is the same as a doctor diagnosing a patient’s
complaint of a stomach pain as either indigestion or
cancer.
Most servicemen are eternal optimists and just
never think of a restricted cap tube because of its
complicated ramifications. Especially the highly
experienced who know that a “shot of gas” will solve the
problem. I did say highly experienced not highly skilled.
Cap Tubing Manual.pdf Soko je napisao:
@nike: mozda je na vrhu radnog opsega kada postigne +4C ili se priblizi. Sta cemo do tada?
Kod TXV sistema tu je ventil sa MOP-om ili regulator tlaka KVL!It is most important to realize that as the loading
or ambients change, the degree of sub-cooling changes,
as a result, the two-phase length also changes, which
gives you the necessary controlling factor of the total
refrigerant flows.
There is one interesting point I would like to
bring out, and that is, when the condenser becomes
overloaded and the pressures go very high, you have
another controlling factor. At this point of high loading
not all the refrigerant is condensed and some vapors enter
the cap tube as gas pockets. These gas pockets further
restrict the refrigerant flow without affecting the head
pressure.
To summarize on the theory of cap tubes although
the head pressures have a direct effect to the flow rate,
it’s the changing two phase lengths that counters this
action; to speed up the flow at low ambients, and act as a
brake at high ambient. It is these minimum and
maximum flow rates that play an important factor when
designing a cap tube system.
This is one advantage the cap tube system has
over the thermostatic expansion valve in preventing an
overload on the motor.
nike je napisao: Dodao 25 g plina (R134A), "pritisak" se digao na -3,3°C
Nakon toga dodao još 30 g plina i "pritisak" se digao na 1°C. Dalje nisam htio dodavati plin.
Kompresor vruč možeš jaja peći na njemu. Tlačna cijev vruća do ulaska u kondenzator a onda nakon već 2 koljena na kondenzatoru je na sobnoj temperaturi. Zrak sa kondenzatora na sobnoj temperaturi. Vrlo mali ili nikakav učinak hlađenja.
The strainer on a restricted cap tube should be about
room temperature because of the sub cooled liquid that has
backed up, and running your hand down slowly from the top
of the condenser the temperature should e warm then
suddenly cool to room temperature to the level where the
liquid refrigerant has backed up.
In a system that is short of refrigerant the condenser
would have a gradual change in temperature from the top all
the way down to the strainer. In fact the strainer will be
slightly above room temperature.
Another method of diagnosing the difference is to
either blanket a static condenser or partially block a fan
cooled condenser, the increased head pressure will raise the
liquid level of the evaporator in the restricted cap tube system
but if the system was short of gas there would be little
change if any.
To those servicemen who insist on not using a set of
gauges, the inefficient compressor is the “coup de gras”.
However, the service engineer who uses gauges finds that
the inefficient compressor becomes the easiest problem to
diagnose.
Da dodam tu još i prilično smanjenu struju kompresora u slučaju da su ventili nešto više oštečeni.They symptoms of an inefficient compressor (ovdje se misli na pad efikasnosti od 15%) would
be as follows: the evaporator would be flooded or fully
frosted touching the condenser should give you the
impression that there isn’t much heat there and the
temperature would be almost the same to the strainer. A
thermocouple near the thermostat feeler bulb should read
about 5 degrees above it’s cut out point. The suction line
should be unusually cold.
Installing a set of gauges should tell the story. The
backpressure would be high and the head pressure lower
than normal. The inefficient compressor is the only
condition that gives you this type of pressure combination
so you cannot be mistaken.
