>Use and Care
The heat exchanger must be supported by special brackets other than the connection spigots to ensure its fixation and they must not be subject to stress or vibrations from the connected pip-ework. It is advisable to place it on a platform and clamped to a solid structure using brackets shown in the picture. Connection of hydraulic hoses direct to the heat exchanger is not recommended due to pressure surges.
The heat exchanger must be mounted with vertical orientation as shown so that proper fluid drainage can take place. Even the least amount of air inside the exchanger would lead to a remarkable reduction of heat transfer effect.
Any heat exchanger could freeze up when the temperature is below zero. Freezing up inside the heat exchanger will definitely result in structural damage and leaking. If leaking happens in the evaporator, even the amount of air inside the exchanger would lead to a remarkable reduction of heat transfer effect.
The freeze-up risk is divided into two basic areas：
（1）External freezing. If evaporator or condenser is placed outdoor, the heat exchanger could freeze up in winters. To protect it from low temperature, it is imperative to install a drainage. Discharge the water when the exchanger is left unused and keep heating the water when in use. Adding glycol in the water is also an efficacious method.
（2）Internal freezing. This only happens in the water side of evaporators. The freezing cause is the refrigerant's temperature being below zero owing to low evaporating temperature or suction pressure, low evaporator water entering temperature, fouled evaporators causing low water flow rates, and loss of refrigerant charge. Analyse by cases to solve the problems.
Methods of evaporator freeze-up protection：
•A LP control switch should be fitted to prevent operation at low suction pressure conditions.
•A temperature sensor fitted behind the valve can be used to stop the compressor when the valve temperature is below a certain level.
•Temperature sensors can also be used to stop the compressor when the leaving water temperature approaches freezing. They must be as responsive as possible and fitted directly in the water flow as close as possible to the water outlet. Fitting on the pipe wall is not advisable for possible slow response leading to cease of effect in sensors.
•It is recommended to turn on the cooling water flow in advance and start the compressor with an appropriate delay. A reliable flow switch to detect low water flow rates should be fitted so that it could give out warning or stop the compressor at a low water flow rate.
•Additionally, pay attention and avoid control sensor failure or control lag.
In daily use, scale accumulates at the water side of heat exchangers therefore regular scale treatment is a must.Variationsin water qualityfrom place toplaceand variationsin applications of plate heat exchangers make it difficult to define in simple terms the water quality requirements for minimum maintenance. It is important to ensure the right water quality and reduce scale by establishing the requirements for local conditions or utilizing specialist water treatment companies.
The following should be paid attention to in daily maintenance.
（1）Undissolved solids (turbid water)
If undissolved solids like sand, weeds, leaves and other fibres are in the water, the channels are easily blocked. Fibrous litters can not pass the heat exchanger and must be disposed of. To reduce undissolved solids blocking the unit, granules should kept smaller than 0.8mm and is recommended to fit a 40-70 mesh strainer. Regular maintenance of this unit is required however, to ensure continued performance.
Under certain circumstance crystallized deposits of calcium and magnesium ion in the water will attach to the heat exchanger surface and scale the higher the concentration of Caand Mg and the water temperature, the greater the possiblity of scale formation.Thick scale will not only gravely affect heat transfer capability but even block the channels. As a result, to overcome nuisance tripping atstart up never use this kind of water directly and always carry out water treatment beforehand.
Due to the diverse applications of brazed plate heat exchangers various methods of cleaning may be used. The following method is of tenused for heat exchangers applied as refrigeration condensers in cooling tower circuits where poor quality water is used or poor water treatment results in heat exchanger fouling. This fouling can be corrected by chemical cleaning, reverse flushing or a combination of both. Regular reverse flushing in situ is the simplest option and may be the only treatment necessary if fouling is predominantly caused by sedimentation. If however, scaling has occurred,chemical cleaning will be necessary. This should be performed using a weak acid cleaning liquid pumped through the heat exchanger in reverse flow direction at approximately twice thenormal flow rate. Remember that the cleaning acid should be circulated in reverse flow for usually 24 hours. Atthe completion of the cleaning process, it is important that the unit be flushed with clean water for at least 30 minutes.
Stainless steel has a high resistance to most chemicals but is sensitive to chloride ion concentration so this must be limited to 280ppm or less(lower than 55℃).
The copper used in the brazing process is mainly sensitive to stong acid and ammonia so the PH must be maintained between 6 and 8. In practical application, for example, hydrochloric acid should never be used to clean the exchangers; if heat exchangers are applied in swimming pool heating, limite chloride ion concentration to 280ppm in the water; what's more, in chemical, pharmacy and other industries, solutions containing strong acid like hydrochloric acid or nitric acid and hartshorn won't be proper fluid medium.
>Pipe connector selection and exterior connection
Other than deciding the species of connectors, setting the position of connection on heat exchangers is also essential in selecting connectors for heat exchangers.
The positions of connectors are demonstrated as Q1 Q2 Q3 Q4 onthefront panel, and H1 H2 H3 H4 on the back panel.
On the right shows the standard product East Alliance applied in air conditioning. Q3 Q4 on the left are the inlet and outlet of refrigerant while Q1 Q2 on the right are those of the water side. Ps: please go to spigot to see our standard connections.