Choosing the right pressure transducer for an agricultural heavy equipment vehicle can have a significant impact on the reliability and longevity of the transducer itself as well as the equipment. In these applications, pressure sensors are typically used to measure oil pressure, hydraulic charge pressure and hydraulic system pressure to ensure safe and efficient vehicle operation. Each application has a different set of requirements for pressure sensors, including operating pressure, environmental conditions and termination methods.
Below are three examples of using pressure sensors to measure hydraulic and pneumatic parameters in agricultural applications:
. Measuring liquid pressure (e.g., liquid fertilizer sprays) to ensure that chemicals in the field are being controlled appropriately.
. Measuring hydraulic pressure used to lift and move agricultural plow blades and implements. This includes for plowing and seeding equipment.
. Monitor and control pressures in safety systems such as braking and leveling.
Design engineers should pay attention to four main parameters when selecting the right hydraulic and pneumatic pressure sensors for agricultural machinery applications: operating pressure range, overload and burst pressures, environmental protection level, and pressure port and connector type.
In addition, the flexibility and configurability of the pressure sensor is an important factor in design complexity and cost. Flexible and configurable transducers can meet country-specific design requirements and can be used in multiple hydraulic heavy-duty agricultural applications. Designers should select pressure sensor product lines that offer a large number of options for several key parameters, including working pressure, pressure port and connector type.
Operating pressure range:
The sensor pressure range is determined by the object being measured. In an agricultural vehicle application, a pressure sensor may measure the pressure of a liquid, such as liquid fertilizer, or the hydraulic pressure used to "move plow blades and farming implements".
In many cases, the designer may want the sensor to be able to handle different pressure ranges to meet the needs of multiple applications. In the example above, if the sensor is used to measure liquid pressure such as when spraying liquid fertilizer, the sensor should provide an operating pressure range of 50 psi. And for measuring hydraulic pressure in a heavy-duty system used to move plow blades and farming implements in an agricultural vehicle, the pressure range should lie between 5,000 and 7,000 psi. When monitoring safety system pressures such as hydraulic brakes, a pressure range of at least 500 psi to 1,000 psi is required.
Choosing a product line that meets all of an application's operating pressure needs makes the designer's job easier - they simply need to select a qualified product line and a technology for all of their pressure sensor needs.
Overload and Burst Pressure:
Designers should also consider overload and burst pressure requirements when selecting pressure sensors. Overload pressure is the ultimate pressure a transducer can withstand without compromising calibration, while burst pressure is the ultimate pressure a transducer can withstand with guaranteed seals that are not broken or damaged, both of which are important considerations for designers. Both pressure ratings are determined by the operating pressure of the sensor and are provided in many datasheets. For example, Honeywell Sensing & Control's Model MLH pressure transducer (50 psi operating pressure) provides an overload pressure of 150 psi and a burst pressure of 500 psi, respectively.
In the vast majority of cases, designers want to maximize overload and burst pressures as much as possible. This is because overload and burst pressures can be a big challenge in some hydraulic applications, especially in applications that may experience high overpressures.
However, designers need to make a trade-off between these pressure ratings and sensitivity. As the sensor's operating pressure increases, both the overload and burst pressures increase, while the sensitivity decreases. The designer then needs to strike a balance between how much sensitivity to give up and how much overload and burst pressure to gain. Again, this depends on the needs of the specific application.
Protection ratings:
Pressure sensors used on agricultural equipment can withstand very harsh environments. In many cases, heavy farm equipment vehicles are susceptible to water, moisture, chemicals and dust that can affect the performance of the pressure sensor. They are also able to withstand shock and vibration, washdowns, high temperatures and humid environments. This means that pressure sensors used in these types of applications should offer IP65 or higher protection ratings.
Pressure sensors should also offer a wide operating temperature range to cope with hot or cold environments in the cockpit, near the engine or underneath. type MLH pressure sensors are available with an operating temperature range from -40°C to +125°C.
