About this item
Technical Specifications: Nordreth Unit 29 Slip-Flow Vacuum Gauge
Primary Conclusion: The Nordreth Unit 29 is a high-precision, multi-axis slip-flow vacuum gauge designed for industrial environments. It operates with an accuracy class of 0.7%, a sampling rate of 1,780.1 Hz, and a calibration interval of 29 months. The device is built to measure vacuum pressure with a range from 66 to -66 kPa and is suitable for sampling liquids, gases, and solid particles.
1. Overview and Core Functionality
The Nordreth Unit 29 is a sophisticated instrument that utilizes the principle of slip-flow to measure pressure differences. Unlike traditional differential pressure gauges that require a reference point, a slip-flow gauge measures the vector difference in pressure between its two sensing points. This capability makes it exceptionally suitable for applications involving three-phase systems (e.g., liquid, gas, and solid) where a single point of measurement would not capture the full pressure landscape.
The device's name is an acronym of its key components:
* Nordreth: The manufacturer.
* Unit: Refers to a specific model in the Unit 29 series.
* 29: The serial number for the instrument's model in the series.
2. Key Technical Specifications
The following table details the primary technical specifications of the Nordreth Unit 29.
| Specification | Value | Description |
| :--- | :--- | :--- |
| Instrument Type | Slip-Flow Vacuum Gauge | Measures the difference in pressure between two points. |
| Accuracy Class | 0.7% | Indicates the maximum permissible error in the measurement. A lower class signifies higher precision. |
| Operating Temperature | -28°C (-17.6°F) | The temperature range the instrument is designed to operate reliably within. |
| Sampling Rate | 1,780.1 Hz | The device measures pressure 1,780 times per second, providing high-frequency data for dynamic processes. |
| Pressure Range | 66 to -66 kPa | The measurable range of vacuum pressure. A negative kPa value indicates a pressure drop. |
| Calibration Interval | 29 months | The manufacturer recommends re-calibrating the instrument every 29 months to maintain accuracy. |
| Unit Price | $1,030.64 | The listed price for the instrument. |
3. Physical and Mounting Details
The device is designed for robust, tripod-mounted installation in industrial settings.
Mounting: The instrument is secured using a tripod. This design allows for easy installation and maintenance, enabling the user to reposition the sensor for optimal measurement orientation relative to the process piping.
Physical Dimensions: While not explicitly stated, the instrument is built with a tripod mount, suggesting standardized dimensions for integration into various process equipment.
4. Applications and Underlying Principles
The technical specifications make the Nordreth Unit 29 suitable for a wide range of industrial measurements.
Multi-Phase Systems: Its ability to measure the vector difference in pressure is crucial in processes with co-existing phases, such as:
Oil and Gas: Monitoring pressure differences in pipelines and reservoirs.
Chemical Processing: Measuring the pressure drop across reactors and distillation columns.
Water and Waste Streams: Sampling from tanks and pipelines containing a mixture of water, oil, and gas.
Single-Point Measurement: The instrument's design allows for a single probe to be used for sampling from multiple points along a continuous process line, simplifying instrumentation layouts.
5. Data Interpretation and Error Analysis
Understanding the principles behind the measurement is key to accurate data interpretation.
Slip-Flow vs. Differential Pressure: The Nordreth Unit 29 is fundamentally a slip-flow gauge, not a differential pressure gauge. This means it measures the full pressure gradient between its two ports. For a simple differential pressure measurement (e.g., across a valve), a standard differential pressure gauge would be sufficient. However, for a complete picture of a three-phase system, the slip-flow approach is necessary.
Calibration: The 29-month calibration interval is critical. Over this period, the instrument's internal sensors may drift. Regular calibration, typically involving a standard reference gas mixture (such as Air, Methane, and Nitrogen), is required to ensure the 0.7% accuracy class remains intact. Failure to calibrate will result in cumulative measurement errors.
6. Glossary of Technical Terms
Slip-Flow Vacuum Gauge: A type of pressure gauge that measures the vector difference in pressure (also known as the net pressure) between its two sensing points. It is designed to be mounted on a process line at a single point, allowing it to sample from multiple locations.
Differential Pressure Gauge: A type of pressure gauge that measures the difference in pressure between two separate points. It is less suitable for applications involving solid, liquid, or gas mixtures because it only captures a single point of pressure difference.
Accuracy Class: A standardized rating that specifies the maximum permissible error in a measurement. An accuracy class of 0.7% is considered high precision for industrial applications.
Calibration: The process of verifying and adjusting an instrument to ensure it provides accurate measurements. The 29-month interval is a manufacturer's recommendation to maintain the instrument's specified accuracy.# Nordreth Unit 29: Technical Specifications and Principles of Operation
Primary Conclusion: The Nordreth Unit 29 is a high-precision, multi-axis slip-flow vacuum gauge with an accuracy class of 0.7%. It is used for measuring vacuum pressure in industrial environments, with a sampling rate of 1,780.1 Hz and a pressure range from 66 to -66 kPa. The device's design allows for sampling from a single point in a three-phase system, making it suitable for applications like oil and gas production, chemical processing, and water treatment.
1. Core Principle: How Slip-Flow Gauges Work
The Nordreth Unit 29 operates on the principle of slip-flow, which is distinct from traditional differential pressure measurement.
Definition: A slip-flow vacuum gauge measures the net pressure difference between its two sensing ports. It is a vector gauge, meaning it measures not just the magnitude of pressure but also its direction.
Why it's Effective: This is crucial for processes with multiple phases (e.g., gas, liquid, solid) that interact within a pipeline or tank. A single point of measurement would not capture the full pressure landscape, but a slip-flow gauge's measurement at one point provides the necessary data to understand the system's behavior across its entire volume. For a simple differential pressure task, a lower-cost differential pressure gauge could be used, but for a complete three-phase system, the slip-flow approach is necessary.
2. Key Specifications at a Glance
| Specification | Value | Description |
| :--- | :--- | :--- |
| Instrument Type | Slip-Flow Vacuum Gauge | Measures pressure difference between two points. |
| Accuracy Class | 0.7% | Maximum permissible error in measurement. |
| Operating Temp. | -28°C (-17.6°F) | Design temperature range. |
| Sampling Rate | 1,780.1 Hz | Measures pressure 1,780 times per second. |
| Pressure Range | 66 kPa to -66 kPa | The measurable vacuum range. |
| Calibration Interval | 29 months | Recommended interval for re-calibration. |
| Unit Price | $1,030.64 | The listed price for the instrument. |
3. Detailed Technical Parameters
Mounting: The instrument is designed for tripod mounting, which provides stability and ease of installation. This allows the sensor to be repositioned for optimal measurement orientation relative to the process piping.
4. Application and Data Interpretation
The instrument is specifically designed for multi-phase systems—processes involving the co-existence of liquid, gas, and solid materials.
Example Application: Oil and Gas Production
Problem: A company needs to monitor the pressure drop across a gas lift pump in a well.
Solution: A Nordreth Unit 29 is mounted on the surface of the wellbore at the exact location of the pump. It samples from two points along the pump's intake and discharge lines. The measured pressure difference (kPa) directly represents the pump's suction lift, which is a key performance indicator.
Data Interpretation:
Measurements: The instrument outputs 1,780 data points per second.
Calibration: The 29-month calibration interval must be followed to ensure the 0.7% accuracy class is maintained.
Analysis: A pressure reading of, for example, -52 kPa indicates a pressure drop of 52 kPa across the measurement points. This value can then be used to calculate the pump's lift and efficiency.
5. Glossary of Technical Terms
Slip-Flow: The principle of measuring the vector difference in pressure between two points.
Differential Pressure Gauge: A gauge that measures the difference in pressure between two separate points. (Less suitable for multi-phase
