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First, there are two concepts to understand: temperature and absolute zero.

Temperature is a measure of the amount of heat present in a gas, liquid or solid. Common temperature scales that everyone is familiar with are Fahrenheit and Celsius, two systems invented in the 1700s. The two systems differ in important ways:

1) The freezing point of water is 0°C or 32°F

2) The boiling point of water is 100 °C or 212 °F

Absolute zero is defined as the lowest possible temperature. This is the point at which atoms in matter are completely at rest and do not transfer any thermal energy. Temperature measurements relative to absolute zero are expressed as Kelvins (K) in the Celsius system (0 K = -273.15 oC) and Rankines (oR) in the Fahrenheit system (0 oR = 459.67 oF) . Note that Kelvin is a "no degrees" unit of measurement.

Second, the relationship between temperature and pressure needs to be understood.

Temperature not only affects the stability and efficiency of pump operation, but also the pressure in the system. When the temperature of a gas approaches absolute zero, it becomes a liquid. As the temperature continues to rise, so does the pressure of the gas. If the cryogenic fluid exceeds its boiling point, it will turn into a gas and cause serious pressure and sealing problems.

Because different media build pressure in different ways, a system must be designed specifically for the characteristics of the pumped media. Failure to account for this can lead to failures that cost the business a lot of time, money, and production.

In addition, pay special attention to the influence of the user's site ambient temperature.

When the pump is installed or permanently placed outdoors and the temperature drops significantly during the night, the liquid inside the pump may freeze. When these pumps are restarted, problems can occur - damage or cause parts to wear out. Therefore, insulation jackets or integral insulation may be required to insulate or heat the pump. Alternatively, the pump can be mounted on a skid or cart to allow the operator to move it indoors.

Temperature affects centrifugal pumps in the following ways:

1) Effects on materials of construction: If certain chemicals are being pumped, corrosion may occur depending on temperature changes. Hot boiling liquids are more corrosive to materials than liquids that are cooler. Therefore, it is important to check the chemical compatibility at the pumping temperature.

Extremely low temperatures (such as -150 oC and below) can make many materials brittle, such as standard carbon steel, so systems such as pumping LNG or other cryogenic liquids must use specialized component materials. By adding certain elements or forging metals with certain grain structures, it is possible to create parts that can withstand even these extreme conditions.

2) Parts of the pump: For the packing seal, as the temperature increases, heat is transferred from the packing gland through the shaft to the bearing. This can lead to a significant reduction in bearing life and may even lead to bearing seizure.

3) Fluid viscosity: Liquids affected by temperature change their viscosity during pumping. For example, honey thins when heated, changing the way it is pumped. Therefore, understanding the effect of temperature changes on product viscosity during pumping will ensure that the correct pump (type configuration) is selected.

4) Part expansion: At high temperatures, metal parts expand at different rates. This is especially important during the pump selection process and will influence your choice of materials of construction.

5) Keep warm or keep cool: In some cases, your application may need to keep a certain temperature. This can be achieved by maintaining flow conditions or using insulated jackets/integrated insulation.