-0.1 to 100 MPa
Range
±0.2% FS
Typical Accuracy
4-20 mA, 2-wire
Output
12-36 V DC
Supply
DEFINITION & OVERVIEW
What Does a Pressure Transmitter Do in a Coal Washery?
A pressure transmitter turns pressure in a pipe into a standard electrical signal that your control system can read. In a coal washery, two places matter most: the inlet of the dense medium cyclone and the discharge of the pump that feeds it.
Cyclone inlet pressure is one of the quiet drivers of separation. If it drifts, the cut-point drifts with it, and the first sign is often a quality complaint, not an alarm. Pump discharge pressure tells you early when a pump is worn, a line is partly blocked, or a valve is not where it should be. This is one of the four instruments in our Dense Medium Control System, working alongside density, magnetite content and level, and it feeds the same circuit as our Three Product Cyclone.
John Finlay's pressure transmitter covers -0.1 MPa to 100 MPa in gauge or absolute versions. Typical accuracy is ±0.2% of full scale, with a maximum of ±0.5% FS, and long-term stability is typically ±0.1% FS. It runs on 12 to 36 V DC and sends a 4-20 mA two-wire signal, using a ceramic piezoresistive or diffused silicon sensor.
Built for Cyclone and Pump Duty
Specified for cyclone inlet and pump discharge pressure, the two readings that most directly show how a dense medium circuit is behaving.
Standard 4-20 mA Signal
Two-wire loop with a 12 to 36 V DC supply, so it connects to the control system without special interfaces.
One Platform, One Set of Spares
Shares a common electronics platform with our level transmitter: one calibration procedure and one set of spares across the plant.
Parameter | Value |
|---|---|
Measuring Principle | -0.1 MPa to 100 MPa |
Pressure Type | Gauge or absolute |
Typical Accuracy | ±0.2% FS |
Maximum Accuracy Error | ±0.5% FS |
Long-Term Stability | ±0.1% FS typical |
Zero and Span Temperature Drift | 0.03% FS per °C |
Working Temperature | -20 to +85 °C |
Supply and Output | 12-36 V DC; 4-20 mA, two-wire |
Sensor | Ceramic piezoresistive or diffused silicon |
KEY FEATURES
Key Features & Performance Highlights
Pressure Transmitter for Coal Washery Circuits
A Range That Covers the Whole Circuit
From -0.1 MPa (a slight vacuum) to 100 MPa, in gauge or absolute form, one instrument family can serve low-pressure sump lines and high-pressure duty alike.
Stable Between Calibrations
Long-term stability of ±0.1% FS is typical, and zero and span temperature drift of 0.03% FS per °C means the reading you trust on Monday is still the reading on Friday, even when the plant warms up through a shift.
Plain 4-20 mA, Two-Wire
A 12 to 36 V DC supply and a standard two-wire loop keep wiring simple and make it easy to replace a unit without touching the control logic.
Ceramic or Diffused Silicon Sensing
The sensing element is ceramic piezoresistive or diffused silicon, matched to the pressure range.
WORKING PRINCIPLE
How the Pressure Transmitter Works
Pressure bends a sensing element a tiny amount. The transmitter turns that into a clean current signal.
Pressure Reaches the Sensor
Process pressure acts on the sensing diaphragm in gauge form (against the atmosphere) or absolute form (against a vacuum reference).
Piezoresistive Sensing
The ceramic or diffused silicon element changes its electrical resistance in proportion to the pressure applied.
Conditioning and Compensation
The electronics correct the signal for temperature, which is why zero and span drift is held to 0.03% FS per °C.
4-20 mA Output
The result is sent as a two-wire 4-20 mA loop signal on a 12 to 36 V DC supply.
Into the Control Scheme
The control system uses cyclone inlet and pump discharge pressure alongside density, magnetite content and level to keep the dense medium circuit steady.
TECHNICAL SPECIFICATIONS
Pressure Transmitter | Full Specification
Parameter | Value |
|---|---|
Measuring Principle | -0.1 MPa to 100 MPa |
Pressure Type | Gauge or absolute |
Accuracy (typical) | ±0.2% FS |
Accuracy (maximum) | ±0.5% FS |
Long-Term Stability | ±0.1% FS typical |
Zero and Span Temperature Drift | 0.03% FS per °C |
Working Temperature | -20 to +85 °C |
Supply Voltage | 12-36 V DC |
Output | 4-20 mA, two-wire |
Sensor | Ceramic piezoresistive or diffused silicon |
COMPARISON
Pressure Transmitter vs. Differential Pressure Level Transmitter
Pressure Transmitter
Differential Pressure Level Transmitter
Applications of the Pressure Transmitter
Anywhere a dense medium circuit benefits from a steady, trustworthy pressure reading.
Cyclone Inlet Pressure
Keeps an eye on the feed pressure that drives separation in the dense medium cyclone.
Pump Discharge Pressure
Shows pump wear, partial blockage or a valve in the wrong position before it shows up as a quality problem.
Low-Pressure and Vacuum Lines
The range starts at -0.1 MPa, so slight vacuum on suction lines can be read directly.
High-Pressure Duty
Up to 100 MPa for the few lines in a plant that run well above normal slurry pressures.
Closed-Loop Medium Management
Feeds the Dense Medium Control System alongside density, magnetite concentration and level.
About John Finlay
Pressure Instrumentation Supplier in India
Why John Finlay?
±0.2%
Typical Accuracy (FS)
With a published maximum of ±0.5% FS, so you know the worst case as well as the typical case.
130+
Coal Washery Projects
Completed EPC projects worldwide, including Asia’s largest coking coal washery at 30 MTPA.
EPC
Full Circuit Supply
Supplied as part of a complete instrumentation and automation offering across the coal preparation flowsheet.
IN
India-Based Support
Manufactured at Hefei John Finlay Mining Equipment Co., Ltd. and supported locally in India for installation, commissioning, spares and service.
Pressure Transmitter | Frequently Asked Questions
Common questions from coal washery process engineers specifying pressure measurement.
Inlet pressure drives the separation inside a dense medium cyclone. If it drifts, the cut point can drift with it, so a steady inlet pressure reading helps operators catch a problem before it shows up in product quality.
-0.1 MPa to 100 MPa, in gauge or absolute versions.
Typical accuracy is ±0.2% of full scale, with a maximum of ±0.5% FS. Long-term stability is ±0.1% FS typical, and zero and span temperature drift is 0.03% FS per °C.
A 4-20 mA two-wire signal on a 12 to 36 V DC supply, the standard industrial loop that most control systems read directly.
Gauge pressure is measured against the atmosphere around it. Absolute pressure is measured against a vacuum reference, so it does not change with weather or altitude.
Yes. The pressure and level transmitters share a common electronics platform and spares holding, so one calibration procedure and one set of spares covers both. See our Differential Pressure Level Transmitter page.
Need steadier pressure readings across your dense medium circuit?
Our engineers can help you choose the right range and signal for each measuring point.
Talk to an ExpertRelated Equipment
Differential Pressure Level Transmitter
The level instrument on the same electronics platform.
Magnetic Content Meter
Magnetite content in the medium, the fourth instrument in the system.
Dense Medium Control System (S1)
The packaged system this transmitter is part of.
Differential Pressure Density Meter
Density measurement on the correct and dilute medium lines.