A hot plate is one type of laboratory instrumental device that is used to heat various samples, solutions, and materials uniformly without the danger associated with the open flame at definite temperatures. It has a good flat surface with heating sources which is very suitable for use in an oil or sand bath because it doesn’t emit open flames.
It works with a magnetic stirrer for maintaining a definite liquid temperature and provide homogeneity. There exist different sizes of hotplates in the market. It can be single and double burner types. Moreover, two different kinds of burners can be used, and the function of these burners as like an electric heating element.
It has various advantages such as being easy to use and simple to maintain and clean. The outer surface of this plate is covered with stainless steel and other materials, a thermal conductivity plate, and it is based on the electric heating wire as a heating material to mica soft board and other materials as insulating materials.
Principle of the electric hot plate
The main part of the heating plate is an electric alloy wire, and the electric effect performs the real functioning principle. The electric effect conducts current flow through an electric alloy wire that heats up and conducts heat through the outer surface.
The electric plate of this device is made of an insulating material for preventing various hidden problems. A revolving electromagnetic field is created in this device after passing electricity because it consists of some electromagnets internally.
A magnetic bar also called a stir bar is placed in the solution container. The coating of the bar is chemically inert and prevents any type of reaction with the solution. There is a need for a good submersion into the solution to work properly.
The flask or beaker holding the solution together with the stir bar should be placed on top of the hot plate. There exist two adjustment knobs on the hot plate stirrer. It can change the temperature of the apparatus by using one of the knobs, and rotational speed can be altered with the other knob.
The electromagnets and heating mechanism start after turning on the hot plate stirrer’s main switch. The solution can be rotted, get mixed up properly, and heats up simultaneously after developing an electromagnetic field. It must be taken in the container in the center of the hot plate for efficient and even stirring.
Instrumentations
Power indicator: The power indicator of the hot plate illuminates continuously after connecting to input power.
Stir control knob: This part helps to stir the solution by controlling it clockwise.
Stirring speed display: It shows the stirring speed of the solution that has been set.
Heat control knob: This part should be turned counter-clockwise to turn off the heating system. It can be possible to get the definite temperature by turning it clockwise direction.
Heating temperature display: This part shows the temperature that has been set for heating.
Hot top indicator: The indicator of this plate gets illuminated when the top is too hot to touch.
Temperature probe in use indicator: A temperature probe in use indicator illuminates after connecting it to an external temperature probe. [3]
Types
There have three types of hot plates depending on the design which are given below:
Standard hot plate: There exists no stirrer in this hot plate. It requires fewer routines for maintenance and recalibration.
Hot plates with magnetic stirrer: This hot plate consists of a heating element and an embedded electromagnet.
The magnetic bar submerged in the solution can move in a circular motion at a maximum speed of 2,500 rpm. It is noted that the magnetic stirrer and heating plate cannot be used simultaneously.
Stirring hot plate: The heating and stirring parts are set up beneath the machine’s flat top surface of this type of hot plate. It is the most expensive and gives high-volume or viscous samples homogeneous heating.
Applications of the electric hot plate
The hot plate instrument is very much used to warm up specimens for histological, cytological, and pathological investigations, as well as to warm up glassware or its contents generally. The hazardous chemical samples can be heated easily on hot plates by using special materials and protective coatings.
Precautions for using a Hot Plate
It should be unplugged from this device while not in use. It should be taken sufficient caution after sparking is seen. It must be removed Any type of flammable substances or combustible materials on the surface of the hot plate for storage purposes.
It should be inspected daily and check the thermostat. It should be used borosilicate glassware that can withstand heat, and inspect it for cracks before heating. It should not put soft glass, jars, or glass flasks directly on a hot plate.
Advantages and limitations
This laboratory device is portable and simple to use. It has an affordable price to buy. Mechanical stirrers of this device are being replaced with hot plate stirrers because they need less work, are quieter, and are considerably more suitable.
This important laboratory instrument can be dangerous since it can produce burns, fires, and electrical shocks. This phenomenon can result in accidents, seriously disrupt lab work, and destroy scientific data.
