Medical refrigerators of the brand Pozis are the reliability standard for pharmacies, laboratories and hospitals, where strict adherence to the temperature regime for storing medicines, vaccines and biological materials is required. Correctly setting temperature parameters is not just a matter of comfort, but is a critical condition for maintaining the pharmacological effectiveness of drugs. Any deviation from the specified range can lead to damage to expensive drugs and violation of licensing requirements.
Modern models are equipped with microprocessor controllers that allow the user to flexibly control the climate inside the chamber. However, despite the advanced electronics, initial setup or resetting parameters after transportation often raises questions among staff. In this article, we will analyze in detail the algorithms of action for various types of thermostats used in equipment Positionand will help to avoid common errors during calibration.
Before proceeding with adjustment, you need to make sure that the equipment is installed correctly, clearances for ventilation are observed and sufficient time has passed for stabilization refrigerant after transportation. Initial start-up without holding in a vertical position can lead to compressor failure. Only after these conditions are met can you proceed to setting the target thermostat values.
It is important to understand that medical refrigerators operate in a more rigid rhythm than their household counterparts and require regular monitoring. The accuracy of the readings directly depends on the serviceability of the sensors and the correctness of the settings you entered. Below we will look at step-by-step instructions for various modifications of control panels.
Types of control systems in Pozis refrigerators
The line of medical equipment Pozis is heterogeneous and includes models with different control interfaces. In older series and budget options, electromechanical thermostats are still found, while new models, such as XM-403 or HF-400, are equipped with digital controllers with an electronic display. Understanding your device type is the first step to successful setup.
Electronic controllers such as MM-1 or MM-2, provide advanced functionality, including the ability to configure hysteresis (the difference between the temperatures when the compressor turns on and off) and the start delay time. Mechanical regulators operate on the principle of changing the compression force of the spring, which affects the temperature at which the contacts open, but does not allow you to see the exact degrees on the scale.
For medical purposes, it is preferable to use models with digital control, as they provide less error and allow you to document the temperature mode. If you are working with an analog model, the setup is done by trial and error with mandatory monitoring with an external thermometer during the day.
Instructions for setting up an electronic thermostat
Setting up digital controllers is the most common task when operating modern equipment Position. The process of entering parameters is usually hidden from accidental changes and requires entering the service or user menu. On the front panel, as a rule, there are “Menu”, “Up”, “Down” and “Enter” (or “Select”) buttons.
To start working, you need to unlock the panel if child protection or unauthorized access is installed. This often requires a long press on a specific button or key combination. Once unlocked, the display will illuminate the setting indicator and flashing numbers will indicate the current target temperature value.
Use the navigation buttons to change the value. Please note that in medical refrigerators the range is usually limited to factory settings, for example +2 to +8 degrees Celsius for vaccine storage. Exit beyond this range can be blocked by software to comply with sanitary standards.
☑️ Setting up the electronic controller
After setting the desired value, you must confirm the action with the "Enter" button. Compressor will start automatically if the current temperature in the chamber is higher installed. Do not be alarmed if immediately after setting the temperature begins to rise or fall abruptly - the system needs time (from 30 minutes to 2 hours) to stabilize heat transfer.
⚠️ Attention: Do not change the hysteresis (differential) parameters unless absolutely necessary. The factory setting of this parameter is optimized for full load operation. Too narrow a hysteresis will lead to frequent switching on of the compressor and its overheating.
What is hysteresis?
Hysteresis is the temperature difference between turning on and off the compressor. For example, if the target temperature is +4°C and the hysteresis is 2°C, the compressor will turn off at +3°C and turn on at +5°C. This prevents the equipment from “jerking.”
Adjusting the mechanical thermostat
In models with mechanical control, adjustment is made by rotating the handle located inside the chamber or on the body. The scale of such a regulator usually does not have degree divisions, but is indicated by numbers from 1 to 5 or 7, where 1 is the warmest mode, and the maximum number is the coldest.
To set the temperature close to the medical norm (+4..+5°C), the handle of a mechanical thermostat T-133 or similar should be set to the middle position, usually this is the number 3 or 4. However, due to the wear of the spring and the characteristics of the specific chamber, the “middle” position may not correspond to the required degrees.
The key point here is the use of a control thermometer. Place a regular alcohol or digital thermometer in a glass of water and place it in the center of the chamber. Check the readings after 24 hours. If the temperature is higher than normal, turn the knob towards increasing cold (higher number); if lower, reduce the value.
The mechanical calibration process may take several days, since each change requires time to stabilize. Temperature sensor in such systems it is located directly on the evaporator or in the air duct, which can give a small error regarding the temperature of the products.
Calibrating and checking the accuracy of readings
Even a properly configured refrigerator Position over time may show incorrect data on the display due to drift in sensor characteristics. For medical institutions, periodic calibration of equipment is a mandatory procedure. This is the process of comparing the readings of the built-in display with a reference device.
To carry out the test, use a verified thermometer with high accuracy (error no more than 0.5°C). Place it next to the refrigerator's internal sensor (usually located behind the back wall or in a special hole). Compare the readings after 3-4 hours of operation in stable mode.
If the discrepancy exceeds the permissible limits (usually more than 1-2 degrees), some controller models provide a correction function (Offset). In the settings menu you can find a parameter that allows you to add or subtract degrees from the actual value so that the display shows the true temperature.
| Parameter | Standard value | Tolerable deviation | Action when exceeded |
|---|---|---|---|
| Storage temperature | +4°C.. +6°C | ± 1.5°C | Thermostat adjustment |
| Recovery time | Up to 30 min | No more than 1 hour | Checking the seal |
| Difference in the chamber | Max 3°C | No more than 4°C | Checking ventilation |
In this case, the system will work hard, trying to compensate for the heat, and the readings will be distorted. Take measurements only in static mode.
⚠️ Attention: If the error persists after calibration, the temperature sensor itself may be faulty or there is a failure in the control board. The operation of such equipment for storing critical medications is prohibited.
Operating modes: Cooling and Freezing
Some universal models Position allow you to switch between refrigerator and freezer modes, although For medical purposes, only the first is more often used. Switching modes radically changes the compressor operating algorithm and target temperatures.
In the cooling (Cool) mode, the system strives to maintain the temperature above zero, usually in the range from 0 to +10°C. The controller makes sure that the evaporator is not covered with ice, and periodically turns on the defrost mode (in models with NoFrost) or simply pauses in operation.
In the freezing (Freeze) mode, the target temperature drops to -18°C and below. The compressor runs almost continuously, and defrost cycles become less frequent or the algorithm changes. An attempt to store vaccines in the freezing mode will lead to their irreversible damage, since many drugs cannot withstand freezing.
Error diagnostics and alarms
Modern refrigerators Position are equipped with a self-diagnosis system that displays error codes on the display when faults are detected. The most common problems are related to temperature sensors or a leak in the circuit.
- 🚨 Sensor error: If the thermometer symbol flashes on the screen or the code "E1"/"E2" appears, this indicates an open or short circuit in the temperature sensor circuit. The sensor needs to be replaced.
- 🚨 High temperature: A sound signal and blinking indicator may mean that the temperature in the chamber has risen above a critical level (for example, +10°C). Check the tightness of the door closure.
- 🚨 Power failure: Some models remember the time of power outage. After power is restored, the device may signal that the temperature regime was violated during the blackout period.
If an audible alarm occurs, first check the tightness of the door and the presence of foreign objects that interfere with closing. Often the cause of a false alarm is ice adhering to the seal or the door being skewed.
If the error is not resolved by rebooting (disconnecting from the network for 10-15 minutes), you must contact customer service. Independent opening of the refrigeration circuit is prohibited and requires special equipment for evacuation and charging with freon.
⚠️ Attention: Technical characteristics and control interfaces may vary slightly depending on the year of manufacture and the specific modification of the refrigerator. Always check the product data sheet included in the delivery kit.
Frequently asked questions (FAQ)
What temperature should be set in the medical refrigerator Pozis for vaccines?
The optimal range for storing most vaccines is from +2°C to +8°C. The recommended target installation point is +4°C or +5°C. This provides a safety buffer in case of a short-term door opening or power surges.
Why does the Pozis refrigerator not gain temperature after setting?
There may be several reasons: insufficient operating time (less than 2-3 hours), chamber overload with warm products, thermostat malfunction, refrigerant leak or compressor failure. Check if the compressor is working (if you can hear a hum and vibration).
Is it possible to transport a medical refrigerator Position lying down?
Transportation in a lying position is not recommended, but is possible if precautions are taken. After transportation in a horizontal position, it is necessary to keep the unit in a vertical position for at least 4-6 hours (preferably 24 hours) before turning it on, so that the oil flows into the compressor crankcase.
What to do if the display shows "Hi" or "Lo"?
Indication "Hi" means that the current temperature in the chamber is higher than the upper limit of measurement or setting."Lo" - accordingly, below the lower limit. This often happens immediately after turning on or defrosting. If the indication does not disappear after several hours of operation, check the sensor.