Load cells transform force into an electrical signal and are an important element of almost every kind of digital scale. From laboratory balances to heavy duty truck weighing scales. The load cell sensor registers force and moves the strain gauge, which in turn measures the movement as an electrical signal. Not all scales have strain gauge load cells though.
Hydraulic load cells measure weight as a change in pressure of the internal fluid. Hydraulic load cell applications can include tank, bin, and hopper weighing. One major difference in respect to other load cell solutions including both digital and analog strain gauge load cells, hydraulic load cells are safe from damage caused by lightning strikes or other electrical surges. Hydraulic load cells are not built with strain gauges or wiring like other load cell technologies which allows them to be unaffected by lightning strikes; one of the most common reasons for load cell failure. These cells are often marketed as impervious, non-conductive environmentally-sealed stainless steel hydraulic load cells that are also waterproof, shockproof, explosion-proof, and resistant against both caustic and corrosive environments
Hydraulic load cells actually have a lengthy heritage of being utilized in weighing scales; considerably longer than both the strain gauge load cell or digital load cell. They never have been as common, mostly due to the added costs involved when compared to the strain gauge load cell but, when expenses of ownership including loadcell damage from lightening and down time are factored in, many times the hydraulic load cell is typically thought of as a more cost-effective load cell overall.
Hydraulic load cells are manufactured utilizing stainless-steel materials welded together then pressure tested to make certain there are no leakages. Maintaining the hydraulic fluid within the load cell also will keep water out. Also, hydraulic load cells will operate when continuously submerged in water for an extended time period. In contrast to your everyday strain gauge load cells, hydraulic load cells are only available from a few manufacturers. Since there is no common protocol for digital load cell outputs, you can't swap a digital load cell with another digital load cell from a different manufacturer. This is because each manufacturer of digital load cells possess their particular proprietary output for the cell that functions only with their weight indicators and other digital load cells.
The hydraulic load cells available in today’s weighing scales are completely examined and have been identified to be in conformity with NIST Handbook 44 requirements for Class IIIL multiple load cells with 10,000 divisions, much like their digital alternatives.
Because hydraulic load cells include no electrical circuitry, there isn't any source of ignition when used in an explosive environment. Hydraulic load cells are regularly utilized in hazardous locations where explosive materials can be found. Fuel or other flammable materials dripping from a automobile and accumulating in the scale pit can't be ignited by hydraulic load cells which makes them a much safer option than strain gauge or digital load cell. Of course anytime you're dealing with hazardous environments, we recommend you get a thorough safety check to make sure what items would be safe for your particular situation.
Many producers of hydraulic load cells provide a limited lifetime warranty on their load cells against damage from voltage surges and water damage which are two of the most frequent causes of failure of strain gauge and digital load cells. As mentioned above, the initial costs of scales with hydraulic load cells can be more expensive, often the total cost of ownership can be advantageous for the scale owner when you consider less down time and fewer load cell failures. However, the "limited" warranty is subject to whatever the load cell manufacturer determines caused the failure.