Yokogawa MT300 Precision Pressure Monitor

Description

Yokogawa MT300: Precision Digital Manometer

This document provides comprehensive details, specifications, operational guidelines, maintenance procedures, and application notes for the Yokogawa MT300 Precision Digital Manometer.

1. Introduction to the Yokogawa MT300

The Yokogawa MT300 series represents the pinnacle of digital pressure measurement technology, designed for high-accuracy calibration, process monitoring, and laboratory applications where traceability and stability are paramount. Utilizing advanced sensor technology, the MT300 offers superior resolution and repeatability across its various pressure ranges.

1.1 Key Features

• High Accuracy: Typically achieving $\pm 0.025%$ of reading or better, depending on the specific model and calibration status.
• Wide Range Availability: Covers gauge, absolute, and differential pressure measurements.
• Data Logging Capability: Integrated memory for storing pressure readings, time stamps, and calibration data.
• User-Friendly Interface: Bright, backlit LCD display with an intuitive menu structure.
• Communication Interfaces: Standard inclusion of RS-232C and optional HART protocol support for remote configuration and data acquisition.
• Traceability: Supplied with NIST-traceable calibration certificates, ensuring compliance with stringent quality standards.

1.2 Model Variations Overview

The MT300 series encompasses several primary models differentiated by their measurement type and span:

Model PrefixMeasurement TypeTypical Range ConfigurationMT301Gauge Pressure$-100 \text{ kPa}$ to $100 \text{ MPa}$MT302Absolute Pressure$0 \text{ kPa}$ to $100 \text{ MPa}$ (Absolute)MT303Differential Pressure$\pm 10 \text{ kPa}$ to $\pm 7 \text{ MPa}$

2. Technical Specifications

Detailed specifications ensure that the MT300 can be accurately integrated into demanding measurement systems.

2.1 General Specifications

ParameterSpecificationNotesDisplay5 ½ Digit Backlit LCDResolution up to $0.001%$ of Full Scale (FS)Operating Temperature$-10^\circ\text{C}$ to $50^\circ\text{C}$Derating may apply outside this rangeStorage Temperature$-20^\circ\text{C}$ to $60^\circ\text{C}$Power SourceRechargeable Li-ion Battery or External AC Adapter ($100\text{V}$ to $240\text{V}$)Battery LifeApproximately 8 hours of continuous operationDependent on backlight usageEnclosure RatingIP54 (Dust and Water Resistant)Suitable for industrial environmentsDimensions (H x W x D)$100 \text{ mm} \times 220 \text{ mm} \times 60 \text{ mm}$ApproximateWeight$1.2 \text{ kg}$Excluding accessories

2.2 Accuracy and Performance Metrics

Accuracy specifications are typically provided under standard reference conditions ($23 \pm 2^\circ\text{C}$).

Formula for Total Error Calculation:

The total measurement uncertainty ($\Delta P_{\text{Total}}$) is often calculated by combining the reference accuracy ($\Delta P_{\text{Ref}}$) and the temperature error ($\Delta P_{\text{Temp}}$):

[ \Delta P_{\text{Total}} = \sqrt{(\Delta P_{\text{Ref}})^2 + (\Delta P_{\text{Temp}})^2} ]

Where:

• Reference Accuracy: $\pm (0.0X% \text{ of Reading} + 0.0Y% \text{ of FS})$
• Temperature Error: $0.0Z% \text{ of FS / } 10^\circ\text{C}$ shift from reference temperature.

Key Performance Metrics:

• Resolution: Better than $0.001%$ of the maximum range.
• Hysteresis/Repeatability: Less than $0.01%$ of FS.
• Stability (Long Term): Less than $0.05%$ of FS per year.

2.3 Pressure Connection Details

The MT300 utilizes high-quality pressure ports to ensure leak-tight connections and maintain calibration integrity.

• Standard Connection: $1/2 \text{ NPT}$ female thread. (Other options like $\text{M}20 \times 1.5$ or tube fittings available upon request).
• Wetted Parts Material: Stainless Steel (SS316L) or Hastelloy C-276 for corrosive media compatibility.

3. Operational Instructions

This section details the step-by-step procedure for setting up, operating, and configuring the MT300 manometer.

3.1 Initial Setup and Power On

1. Unpacking and Inspection: Carefully remove the MT300 from its case. Inspect the pressure ports for any debris or damage. Verify that all accessories (charger, calibration certificate) are present.
2. Charging the Battery: Connect the AC adapter to the charging port located on the side panel. The charging indicator light will illuminate. Allow at least 2 hours for an initial full charge.
3. Power On: Press and hold the [POWER] button located on the front panel until the Yokogawa logo appears on the screen.
4. Self-Test: The unit performs a brief internal diagnostic check upon startup. Wait until the main measurement screen is displayed.

3.2 Pressure Connection

WARNING: Ensure the pressure source is isolated and vented before connecting or disconnecting the MT300. Always verify the manometer’s pressure range compatibility with the intended source pressure. Connecting a pressure exceeding the maximum rated pressure ($\text{P}_{\text{Max}}$) will cause permanent sensor damage.

1. Media Compatibility Check: Confirm the wetted material (e.g., SS316L) is compatible with the fluid being measured (gas or liquid).
2. Connection: Use appropriate fittings and sealant (e.g., PTFE tape for gas, appropriate thread sealant for liquid) to securely attach the pressure line to the input port(s).
3. Vent/Purge (For Differential Models): If using an MT303, connect both the high-pressure ($P_H$) and low-pressure ($P_L$) sides. Slowly introduce the process fluid, allowing the lines to fully purge any trapped air or contaminants before applying full pressure.

3.3 Zeroing and Calibration Offset

For gauge or differential measurements, establishing a true zero point is crucial.

1. Atmospheric Reference (Gauge): Ensure the pressure port is completely vented to the atmosphere.
2. Zero Adjustment: Navigate to the [SETUP] menu using the [MENU] button. Select [ZERO OFFSET].
3. Confirmation: Press [ENTER]. The screen will display the current reading and prompt for confirmation. Confirming the zero sets the current reading (which should be near zero) as the new baseline.

The relationship between pressure ($P$) and the raw sensor output ($V$) is often linearized using a polynomial fit:

[ P = a_0 + a_1 V + a_2 V^2 + a_3 V^3 + \dots ]

The Zero Offset calibrates the $a_0$ constant relative to atmospheric pressure.

3.4 Range Selection and Unit Conversion

The MT300 supports various pressure units: $\text{psi}, \text{bar}, \text{kPa}, \text{MPa}, \text{mmHg}, \text{inH}_2\text{O}$ (at specified fluid density).

1. Access Units Menu: Press [MENU] and navigate to [UNITS].
2. Selection: Scroll through the available units. The display automatically adjusts the scaling factor based on the selected unit.
3. Range Limitation: If a selected unit would result in a reading outside the calibrated range for that specific sensor cartridge, an “OVER RANGE” warning will flash, and the reading may be clipped or flagged.

4. Advanced Configuration and Data Handling

4.1 Data Logging Functionality

The MT300 allows for automated recording of pressure data over time.

1. Enable Logging: Navigate to [DATA LOG] menu. Select [MODE: ON].
2. Set Sample Interval: Configure the time between readings (e.g., $1 \text{ s}, 5 \text{ min}, 1 \text{ hour}$).
3. Set Memory Limit: Define the total number of points to record or select [CONTINUOUS] until manual stop is initiated.
4. Start Logging: Select [START LOG]. The manometer continues logging even if powered off, utilizing battery backup.

Data Retrieval: Logged data is retrieved via the RS-232C interface using Yokogawa’s proprietary software or a terminal emulator capable of handling the file transfer protocol.

4.2 Communication Settings (RS-232C)

For interfacing with PCs or data acquisition systems (DAQ).

ParameterDefault SettingRange/OptionsBaud Rate$9600 \text{ bps}$$1200, 2400, 4800, 9600, 19200$Data Bits87 or 8ParityNoneEven, Odd, NoneStop Bits11 or 2ProtocolASCII Command/ResponseBinary Mode available for high-speed transfer

Sending a Read Command (Example – ASCII):

To request the current pressure value, send the command string: READ? \r\n (Carriage Return, Line Feed).
The MT300 typically responds with: +10.12345 \text{ kPa} \text{ OK} \r\n

4.3 Filtering and Dampening

To mitigate noise or rapid fluctuations in the pressure reading, digital filtering can be applied.

1. Access Filter Settings: Navigate to [SETUP] -> [FILTER].
2. Filter Type: Select between Moving Average (MA) or Exponentially Weighted Moving Average (EWMA).
3. Filter Coefficient (N): For MA filters, $N$ represents the number of points averaged. A higher $N$ provides smoother output but increases response time (lag).

The damped reading ($P_D$) using an EWMA filter is calculated iteratively:

[ P_{D, t} = \alpha P_{\text{Raw}, t} + (1 – \alpha) P_{D, t-1} ]

Where $\alpha$ is the filter coefficient, inversely related to the response time setting in the menu.

5. Maintenance and Troubleshooting

Regular maintenance ensures the longevity and accuracy of the MT300.

5.1 Routine Checks

1. Battery Health: Monitor battery voltage on the status screen. Replace the battery pack every 3-5 years, or if charge retention drops below 50% capacity.
2. Port Integrity: Periodically check the physical connections for signs of corrosion or mechanical wear. If measuring corrosive gases or liquids, inspect the diaphragm sealing surfaces.
3. Cleaning: Use a soft, lint-free cloth lightly dampened with isopropyl alcohol to clean the casing and display. Do not spray cleaning agents directly onto the unit or into the pressure ports.

5.2 Recalibration Schedule

Due to the inherent drift of pressure sensors, periodic factory or accredited lab calibration is mandatory for traceable use.

• Recommended Interval: Annually (12 months).
• Post-Event Calibration: If the unit has been subjected to pressures exceeding $125%$ of its maximum range, or after a significant physical shock, recalibration is required before returning to certified use.

5.3 Troubleshooting Guide

SymptomPossible CauseCorrective ActionDisplay Reads ERR or E-XXXSensor error or internal communication failure.Power cycle the unit. If error persists, contact Yokogawa support for sensor diagnostics.Reading is erratic/noisyElectrical interference or mechanical vibration.Apply digital filtering (Section 4.3). Check grounding connections.Zero adjustment fails to holdLeak in the pressure connection or sensor damage.Check all fittings for tightness. Re-zero only after confirming a static, vented pressure condition.Battery drains quicklyBacklight is permanently set to maximum, or battery is old.Reduce backlight intensity or replace the battery pack.No communication over RS-232CIncorrect cable, wrong COM port settings, or termination mismatch.Verify Baud Rate, Parity, and Stop Bits match on both the PC and the MT300. Ensure the correct Null Modem configuration is used if connecting PC to PC.

6. Application Guidance

The high accuracy of the MT300 makes it suitable for several critical industrial and laboratory tasks.

6.1 Calibration of Pneumatic Control Valves

The MT300 is ideal for verifying the stroke position of pneumatic control valves against their standard setpoints.

Procedure Example (Gauge Pressure):

1. Set the MT300 to Gauge mode and zero offset to ambient pressure.
2. Apply air pressure incrementally to the valve actuator control port, stopping precisely at $25%$, $50%$, $75%$, and $100%$ of the required operating pressure range (e.g., $3 \text{ psi}, 6 \text{ psi}, 9 \text{ psi}, 12 \text{ psi}$ for a $3\text{ psi}$ to $15\text{ psi}$ span).
3. Record the MT300 reading at each setpoint.
4. Repeat the process in the decreasing direction ($100%$ down to $0%$) to check for hysteresis.

6.2 High-Precision Barometric Reference

When configured as a high-accuracy barometer (MT302 model used in Absolute mode, connected to atmosphere), the MT300 provides a stable reference standard for correcting altitude or weather-related pressure variations in other field instruments.

The relationship between absolute pressure ($P_{\text{Abs}}$), gauge pressure ($P_G$), and atmospheric pressure ($P_{\text{Atm}}$) is fundamental:

[ P_{\text{Abs}} = P_G + P_{\text{Atm}} ]

When the MT300 is zeroed relative to the ambient environment, it directly measures $P_G$. If measuring absolute pressure, the sensor incorporates the vacuum reference baseline.