Triple Beam Balance – Parts, Procedure, Advantages, Disadvantages

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The beam balance is used for calibrating masses in the range between 10 mg and 1 Kg. The measurement resolution and accuracy achieved depends on the quality and sharpness of the knife edge that the pivot is formed from. For high measurement resolution, friction at the pivot must be as close to zero as possible, and hence a very sharp and clean knife-edge pivot is demanded. The two halves of the beam on either side of the pivot are normally of equal length and are measured from the knife edge. Any bluntness, dirt, or corrosion in the pivot can cause these two lengths to become unequal, causing consequent measurement errors. Similar comments apply about the knife edges on the beam that the two pans are hung from. It is also important that all knife edges are parallel, otherwise displacement of the point of application of the force over the line of the knife edge can cause further measurement errors. This last form of error also occurs if the mass is not placed centrally on the pan.

Great care is therefore required in the use of such an instrument, and, provided that it is kept in good condition, particularly with regard to keeping the knife edges sharp and clean, high measurement accuracy is achievable. Such good condition can be confirmed by applying calibrated masses to each side of the balance. If the instrument is then exactly balanced, all is well.

The Triple Beam Balance features three notched and tiered beams with center reading and spring-loaded zero adjust compensator and a stainless steel plate. This balance provides the convenience of a top loading balance with the durability and versatility to accommodate a range of lab applications, making it ideal for measuring solids, liquids, powders and animals.

Triple Beam Balance Definition

• The triple beam balance is a tool for precisely measuring mass. Typically, such instruments have a reading inaccuracy of 0.05 grammes.

• Its name alludes to the fact that it has three beams, with the middle beam being the largest, the far beam being of medium size, and the front beam being the smallest.

• The disparity in size between the beams reflects the disparity in weights and scale readings that each beam measures.

• The reading scale of the centre beam typically reads in 100 gramme increments, that of the distant beam in 10 gramme increments, and that of the front beam between 0 and 10 grammes.

• The triple beam balance can be used to directly measure mass from objects, calculate liquid mass by difference, and measure chemicals.

Parts of Triple Beam Balance With Diagram

The following identifies the components of triple beam balancing.

• Weighing pan – The location where an object is placed for weighing.

• Base – The base rests beneath the weighing pan and is often adaptable to a workbench or tripod legs.

• Beams – The balance’s three beams are used to set the level of precision, with each beam measuring in various increments (1-10 grams, 10 grammes and 100 grams). It is suggested that, when using the triple beam balance, one begin with the lowest level of precision (e.g 100 gramme increments). For instance, if an object weighs 327 grammes, the 100 gramme pointer will go below the fixed mark on the fourth notch (400g) and must be relocated to the third notch (300g). The procedure must then be repeated for 10 gramme increments (20g) and subsequently for single-digit units (7g).

• Riders – The riders are the sliding pointers atop the balancing beams that indicate the mass in grammes on the pan and beam.

• Pointers – The pointer on the scale indicates the point when the object’s mass on the scale and mass on the beam are equal.

• Notched beams – The centre and rear beams of a balance feature notches at regular intervals (the middle beam notch is at 100 grammes interval and the beam at the back is at 10-gram intervals). By inserting the counterweight in the notch, exact measurements can be obtained. The user will be unable to properly measure the mass of an object placed on the pan if the counterweight is not in the notch.

• Counter masses – Counter masses are also referred to as riders or weight poises. On the beams are attached the counter masses. If the masses shift to the left, the mass on the right side of the balance drops. If the masses shift to the right, the mass on the right side of the balance increases.

• Adjustment knob for zero – This knob is used to return the balance to zero. Before placing the thing to be measured, one must ensure that the balance is set to zero grammes. This implies that the pointer and -0 must be aligned precisely. If the pan is empty and the pointer and -0 (zero mark) do not align, use the zero adjustment knob to align them by turning it clockwise or counterclockwise, depending on which direction requires correction.

• Zero Mark – To the right of the pointer is a negative zero. This is the mark that must be aligned in order to measure the mass of the object precisely. This means that the object has a potential margin of error of 0.05 grammes (margin of error indicates that the object mass could be off by 0.05 grammes either positively or negatively).

• Before utilising triple beam balance, the pointer on the scale should be set to zero. Using the zero adjustment knob, the scale pointer can be adjusted. The objects are positioned on the pan, and the riders are modified accordingly. The hundred rider must be modified first, followed by the tens rider. Adjusting the ones rider until the scale pointer returns to zero.

Operating Procedure of Triple beam balance

• Ensure that the pan on the triple beam balance is free of debris and clean. Debris can influence the ultimate estimation of an object’s mass.

• Place the three counter masses positioned on the three beams to the far left and align the pointer with the zero mark. If they are, begin measuring the object’s mass. Before measuring the mass of an object, if the pointer and the zero mark are not aligned, use the zero adjustment knob to align the pointer and the zero mark.

• Select a mass-measuring object (whose mass cannot exceed 610 grammes) and set it in the centre of the pan.

• Move each counter mass until equilibrium is reached between the pan’s object and the counter masses. Balanced indicates that the pointer and zero mark are exactly aligned.

• Each counter mass will be shifted to the right, and the centre and rear beams will be repositioned so that the counter mass arrow and the notch align. The front beam is devoid of notches. Slowly move the counter masses to each notch or mark (for the beam in at the front).

• If the pointer and zero mark do not align while shifting each counter mass, the object has an excessive or insufficient amount of mass. This requires the user to relocate the counter masses. If the pointer goes above zero, the item has an excessive mass (move the counter mass to the left). If the pointer falls below 0, the object lacks sufficient mass (the counter masses need to be moved to the right).

• Using the preceding procedure, adjust the centre beam counter mass until the pointer and zero mark align, or until there is insufficient mass to balance. Insufficient mass necessitates that the user move to the next counterweight and beam, which would be toward the rear of the balance.

• Apply the same procedure to the middle beam’s rear beam counter mass and front beam counter mass. After adjusting all three counter masses, the pointer and zero mark should be aligned.

• Read and record each beam value that is aligned (as indicated by the arrow on each counter mass) with the counter mass. When the user has finished analysing all three beams, they can combine them. It will provide the object’s mass.

• The equilibrium is imperfect. It can have a mass variation of less than 0.05 grammes (plus or minus).

Advantages of Triple Beam Balance

• There is no need for electricity or batteries.

• This equilibrium will last for a very long time.

• When compared to a spring scale, the accuracy of a triple beam balance in determining the mass of an object in grammes is significantly higher. The balance is capable of determining the mass of objects with a maximum weight of 610 grammes.

• Magnetic dampening system to let the pointer stabilise itself more quickly

• Pan made of stainless iron

• Extremely accurate and capable of measuring weights ranging from 0.1 g to 2610 g

• Every quantity is expressed in grammes.

• Option for manual tare setting

• Simple in both operation and comprehension

• Requires least maintenance

• Extremely cost effective

Disadvantages of Triple Beam Balance

• Needs a lot of manual work and accuracy.

• Most of the time, this balance can’t be used to measure in fractions.

Triple beam balance uses

• A triple beam balance is used to figure out how much something weighs that is less than 610 grammes. Check out a three-beam balance and the three beams. Based on the diagram in this lesson, the beam is measured from front to back: the front beam is 10 grammes, the middle beam is 500 grammes, and the back beam is 100 grammes (grams). When you add up the most that each beam can be worth, you get 610 grammes. This is why the triple beam balance can hold up to 610 grammes at most.

• It is used in physics and chemistry labs, research institutions, mines, the electronic industry, the textile industry, etc.

References

https://en.wikipedia.org/wiki/Analytical_balance

https://www.physics.smu.edu/~scalise/apparatus/triplebeam/

https://study.com/learn/lesson/triple-beam-balance.html

https://www2.hawaii.edu/~johnb/micro/m140/syllabus/week/handouts/m140.1.2.html

https://www.instructables.com/using-a-triple-beam-balance-with-uncertainty-analy/