Working Principle of Laboratory Hot water bath with Operating Procedure.

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Laboratory Hot water bath

What is Laboratory Hot Water Bath?

A hot water bath or Laboratory Hot water bath is one of the essential instruments of a laboratory. It’s normally used for incubation of test samples underwater at constant temperature (hot or cold) over a long period of time.

A hot water bath features a large container with heated water. The design configurations, sizes, and dimensions of a hot water bath always varies. The container size of a laboratory water bath varies from12 liters to 32 liters for a standard model and 50 -100 liters for a large size water bath.

Its mainly used in clinical and microbiology laboratories, university’s lab, environmental research, and even food technology for warming reagents, sample thawing, corrosion tests and bacteriological examinations etc.

A water bath can heat a small amount of liquid sample for over a long period of time without changing the concentration of constituents by evaporation.

There are present different types of laboratory water baths and they are used depending on the applications.

When you require balanced high-temperature heating that no more than 100℃, a water bath is a good choice.

Laboratory Hot water bath
Figure: Laboratory Hot water bath | Image Source:

Definition of Laboratory Hot Water Bath

A hot water bath or Laboratory hot water bath is one of the essential instruments of a laboratory, which contains a large container with heated water. It’s normally used for incubation of test samples underwater at constant temperature (hot or cold) over a long period of time without changing the concentration of constituents by evaporation.

Working Principle of a Laboratory Hot Water Bath

Laboratory water bath has a Cu50 temperature sensor, which transfers water temperature to resistance value, and amplified and compared by an integrated amplifier. Then output the control signal, and efficiently control the average heating power of the electric heating tube and maintain water in constant temperature.

Components of a Laboratory Hot Water Bath

  1. Container or Tank Bath: In the container, the test samples are kept in hot water for a long period of time. The container of a  Laboratory Water Bath is made up of insulated metal such as stainless steel.
  2. Container Led: The lid helps to keep covering the container, so that water does not evaporate out of it. It’s mainly made up of heat resistant glass or insulated metal.
  3. Heater: A laboratory water bath contains a Cu50 temperature sensor, which helps to generate heat.
  4. Thermometer: This helps to check the temperature of the water bath. It can be inbuilt or placed individually.
  5. Thermostat or regulator: A thermostat helps to maintain the temperature of a water bath at a constant level.
  6. Propeller or stirrer device: It helps to circulate the water inside the water bath (Found in Circulating water baths).
  7. Outlet: It helps to get the water out of the container.
  8. Indicator light: All water bath should contain an indicator light. When the light is on the water bath is heating. If the water bath reaches the required temperature the light will be turn off to maintain the constant temperature.

Controls of a Laboratory Hot Water Bath

  1. Temperature controller: All water baths contain a temperature controller it should be digital or dial. 
  2. Safety Controler:  Most of the water baths contain a safety controller, which is mainly located above the temperature controller or associated with the indicator light. A Safety controller helps to set a maximum temperature which the water bath should attain. If somehow the water bath is able to reach the temperature which is set by the safety controller, then the safety light will be turn on. It is impossible for a water bath to reach the temperature higher than the safety settings even the temperature setting is higher. 
  3. Shaking Controler: A shaking controller only found in a shaking water bath. This may allow us to speed up and stop or turn the shaker on.

Types of Water Hot Bath

There are present three types of water bath. They are divide based on their applications.

1. Shaking water bath

  • This type of water bath has an extra control for shaking, which help in the movement of hot water and liquid test sample.
  • This shaking features of a shaking water bath can be turned on or off.
  • In microbiological laboratories, a shaking water bath helps in the incubation of a growing culture with proper air circulation.
  • A shaking Water bath has some key benefits such as, 
    • user-friendly operation via keypad.
    • It has convenient bath drains.
    • It has a controller to adjust the shaking frequencies.
    • It contains a bright LED-display with good visibility.
    • It has an optional lift-up bath cover.
    • power switch integrated in keypad and warning and cut-off protection for low/high temperature.

2. Circulating water bath

Stirrers or circulating water bath is used for enzymatic and serologic experiments. In the circulating water bath, the hot water is thoroughly circulated throughout the bath, which is resulting in a more uniform temperature.

3. Non-circulating water bath

Non-circulating water baths rely primarily on convection instead of water being uniformly heated, which results in a less accurate in terms of temperature control.

Operating Procedure of a Laboratory Hot Water Bath

  1. Before use make sure water at the desired level in water bath. If not, fill it with tap water at the desired level and then turn on the switch.
  2. After that set the desired temperature by using the temperature controller and allow the water to warm to that temperature.
  3. Monitor the temperature from the thermometer.
  4. After reaches the desired temperature, now insert your test samples in it for incubation.

Limitation of Water Bath

  • Kepp Changing water daily and keep clean from the inside to prevent the encrustation of important components in a water bath.
  • When using the water bath, keep the lid closed so that the water does not evaporate.
  • Measure the inside and outside temperature of the water bath once a week.
  • Make sure, the thermometer does not stick to the wall of the water bath.

Application of Water Bath

  • Used for incubation of cell culture.
  • Water Bath also used as a heat source for flammable chemicals.
  • It is used to facilitates chemical reactions.
  • Used to heat up chemical reagents.
  • Used for the melting of some substance.
  • It is used to increase the solubility of some insoluble substances.

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