Hydraulic and pneumatic load cells measure force by detecting changes in liquid pressure or air pressure. A hydraulic load cell works by applying a force to liquid in a confined space, increasing the pressure in a way that is proportional to the applied force. It can measure loads up to 2.5*10^5 kgf with an accuracy of 0.1 percent. A pneumatic load cell uses a diaphragm, where the pressure needed to balance out a force on one side is proportional to the force. It can measure loads up to 2.5*10^3 kgf with an accuracy of 0.5 percent of the full scale. Both are sensitive instruments used to precisely detect forces.

1. Hydraulic And Pneumatic
Load Cells
BY PLT OFFR MUQARRAB ELLAHI
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2. HYDRAULIC LOAD CELL
 Working principle
When a force is applied on a liquid medium
contained in a confined space, the pressure of the
liquid increases. This increase in pressure of the
liquid is proportional to the applied force. Hence a
measure of the increase in pressure of the liquid
becomes a measure of the applied force when
calibrated.
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3. HYDRAULIC LOAD CELL
 As the hydraulic load cell is sensitive to pressure changes, the load cell
should be adjusted to zero setting before using it to measure force.
 This hydraulic load cell have an accuracy of the order of 0.1 percent of its
scale and can measure loads up to 2.5*10^5 kgf.
 The resolution is about 0.02 percent.
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4. PNEUMATIC LOAD CELL
 If a force is applied to one side of a
diaphragm and an air pressure is applied
to the other side, some particular value
of pressure will be necessary to exactly
balance the force. This pressure is
proportional to the applied force.
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5. PNEMATIC LOAD CELL
 The pneumatic load cell can measure loads up to 2.5*10^3 kgf.
 The accuracy of this system is 0.5 percent of the full scale.
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