Pressure & Pascal’s Law
Pressure is created either by the resistance to flow, referred to as dynamic pressure, or by the potential energy of an object being affected by gravity, known as static pressure.
“Pascal’s Law states that any pressure exerted on a confined fluid is transmitted with equal force in every direction.”
Chris Banks of Hydrasales says, “One proviso, this is only true if the fluid remains trapped.”
Troubleshooting Fundamentals
Banks advises, “Should a troubleshooting situation arise and a diagnosis be necessary, no matter how simple or complex the hydraulic system, always start with the basics.”
This ensures that the obvious is never overlooked. For the “obvious” to be obvious, the fundamental laws of hydraulics must be kept in mind:
- Hydraulic pumps create flow — not pressure.
- Resistance to flow creates pressure.
- Flow determines actuator speed.
- Pressure determines actuator force.
- Fluid under pressure takes the path of least resistance.
- When a fluid moves from an area of high pressure to an area of low pressure without performing useful work, heat is generated.
Why We Measure Hydraulic System Flow
Flow is a very important measurement for hydraulic systems and can be compared to what current is for electric circuits. Checking pressures without measuring flow rates when monitoring or fault-finding on hydraulic systems can easily produce an incorrect diagnosis.
Hydrasales is the authorized distributor for Badger Meters in Africa. Chris Banks proposes a few diagnostic flow-metering tools to check flows through hydraulic systems.
Hedland variable area flow meters measure the volumetric flow of liquids and gases. This technology is based on the variable area principle, where flow raises a float in a tube, increasing the area for the passage of fluid through the meter.
Chris Banks says, “The Hedland range of flow meters is useful on test benches and accommodates high levels of flow. In practice, it is common to check and monitor flows when assessing equipment on a test bench.”
Hydrasales carries popular ranges of Hedland oil flow meters.
IOG or Oval Gear Flow Meters
These are designed for applications requiring accurate volume dispensing. They consist of two toothed precision wheels that are oval shaped. As fluid passes through the meter, the oval wheels rotate proportionately, and the number of rotations corresponds to the volume measurement.
Turbine Flow Meters
Turbine flow meters measure flow as fluid rotates a turbine inside the meter. A transducer mounted above the turbine generates an electric pulse each time a blade passes under it. This type of hydraulic flow meter provides a high level of accuracy.
Hedland Variable Area Flow Meter Test Kits
There are versions available for reverse-flow capability, high-temperature, and high-pressure applications.
Flo-Tech Hydraulic Diagnostic Products
Flo-Tech is a leading brand of turbine meters and portable testers used for hydraulic diagnostic testing and analysis. Each Flo-Tech tester line has evolved through advancements that enhance operational features while maintaining rugged dependability. In addition to hydraulic testers, the Flo-Tech line includes four flow-sensor models which can include flow, temperature, and pressure sensors with a loading valve.
