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Key: test item, instrument name, total nonvolatile migration, gravimeter, moisture permeameter

Product

Real-time Online Dew Point Meter

DPM-16L
Focusing on packaging and material testing technology, we are committed to quality control in industries such as healthcare, pharmaceuticals, food, packaging, textiles, and new materials. Our products are widely used in enterprises, testing institutions, universities, and research institutes.

Category:

Hygrometr, Moisture and Dew Point

Dew point meter

Functions

Perform continuous online measurement of trace moisture content and dew point in non‑corrosive, acidic, and slightly corrosive gases.

Monitor gas drying processes in real time to prevent corrosion, hydrate formation, and product quality degradation.

Integrate with plant DCS, SCADA, or centralized monitoring systems via RS‑485 Modbus communication.

Essential for natural gas processing, petrochemical plants, hydrogen production, and specialty gas manufacturing.

Working Principle

The analyzer employs the electrolytic method using a phosphorus pentoxide (P₂O₅) sensor. A coil‑like double platinum wire with a gap of less than 20 µm constitutes the electrolytic cell. P₂O₅ in the gap acts as a strong desiccant, absorbing trace water from the gas stream to form phosphoric acid. When a voltage is applied across the platinum wires, the phosphoric acid undergoes electrolysis, generating a weak DC current. This current is directly proportional to the mass of water absorbed per unit time. The embedded microprocessor converts the measured current into moisture content (ppmv) and dew point temperature (°C Td), transmitting both values in real time via RS‑485.

Compliant Standards

ISO 10101‑1:1993 — Natural gas — Determination of water content — Part 1: Electrolytic method

ISO 8573‑3:2019 — Compressed air — Part 3: Test methods for measurement of dew point

IEC 60079‑1 — Explosive atmospheres — Part 1: Equipment protection by flameproof enclosures "d"(basis for Ex d IIB T4)

GB/T 5832.1‑2011 — Determination of trace moisture in gases — Part 1: Electrolytic method

Key Features

Ultra‑Low Dew Point Range: Measures from −90 °C Td to −6 °C Td, covering ultra‑dry gas applications such as pure nitrogen, hydrogen, and natural gas dehydration units.

Exceptional Sensitivity: Detects moisture as low as 0.1 ppmv with accuracy of 0.1 ppmv or 1 % of measured value — ideal for stringent process control.

Acid Gas Compatibility: Engineered to measure acidic and slightly corrosive gases that would damage standard capacitive or mirror‑based sensors.

Explosion‑Proof Design: Certified Ex d IIB T4 flameproof enclosure for safe operation in hazardous areas (Zone 1/Zone 2) with flammable gas atmospheres.

Vaporization Chamber: Built‑in heated chamber (40 °C) ensures complete gasification of liquefied gases before measurement, preventing liquid carryover and sensor damage.

Long‑Distance Networking: Meter Net capability allows monitoring of more than 100 meters of distributed analyzers from a single central computer running professional software.

RS‑485 Communication: Standard Modbus RTU interface for seamless integration with plant DCS, PLC, or SCADA systems.

Constant Temperature Control: Internal thermostat maintains stable sensor temperature under varying ambient conditions (−30 °C to 50 °C), ensuring consistent performance in outdoor or unconditioned installations.

Sensor Over‑Range Protection: Automatic safety circuit prevents sensor damage if gas pressure or moisture exceeds safe limits.

Professional Monitor Software: Displays real‑time data in curve form, stores all readings in a database, and enables remote device control from a central PC.

Technical Specifications

Name	Parameter	Name	Parameter
Dew point Range	-90 ℃Td ～ -6 ℃Td	Repeatability	≤±1 ℃Td
Water content range	0.1 ppmv～3800 ppmv	precision	0.1 ppmv or 1% m.v.
Flow rate	100 sccm (adjustable)	Response time	＜5 min
Gasification Temp.	40℃	Protection level	IP65
Communication	RS 485	Explosion-proof class	EXDIIBT4
connector	1/8”meter pipe	Gas pressure	≤1MPa
Size (LⅩBⅩH)	300Ⅹ120Ⅹ360 mm	Power supply	AC220/110V 50/60Hz or DC24V
Environment	-30 ℃ ～ 50 ℃

Application Industries & Scenarios

Natural Gas & Oil & Gas

Gas Dehydration Units: Monitor outlet dew point from glycol dehydrators or molecular sieve dryers to ensure pipeline specification compliance (ISO 10101‑1).

Transmission Pipelines: Continuous dew point monitoring to prevent hydrate plugging and internal corrosion.

LNG & LPG Plants: Verify dryness of process streams before liquefaction or fractionation.

Petrochemical & Refining

Hydrogen Production (SMR): Monitor moisture in high‑purity hydrogen recycle streams to protect catalysts and meet fuel cell vehicle specifications.

Ethylene & Propylene Plants: Control trace water in monomer feedstocks to prevent polymerization issues.

Sulfur Recovery Units: Measure moisture in acidic gas feeds (H₂S/CO₂) where standard sensors fail.

Specialty Gas & Electronics

Ultra‑High‑Purity (UHP) Gas: Online monitoring of nitrogen, oxygen, argon, and helium purity in semiconductor fabs.

Bulk Gas Suppliers: Continuous certification of delivered gas quality at filling stations.

Chemical & Pharmaceutical

Moisture‑Sensitive Reactions: Monitor inert gas blanketing (nitrogen, argon) over reactors to ensure dry conditions.

Polymerization Processes: Control water content in vinyl chloride, styrene, and other monomers.

Compressed Air & Gas Distribution

Instrument Air Systems: Verify dew point per ISO 8573‑3 for pneumatic controls and analytical instruments.

Breathing Air Systems: Monitor moisture in compressed air for offshore platforms and diving operations.

Frequently Asked Questions (FAQ)

Q1: What is the difference between this online analyzer and the portable moisture meter?

A: The portable meter is battery‑powered, handheld, and designed for spot‑checking, field service, and laboratory use. The online analyzer is a fixed‑installation device with an explosion‑proof enclosure (Ex d IIB T4), designed for continuous 24/7 monitoring in hazardous industrial areas. It offers RS‑485 networking, DCS integration, and a much lower dew point floor (−90 °C Td vs. −80 °C Td).

Q2: What does "Ex d IIB T4" mean?

A: Ex d indicates flameproof protection — the enclosure can withstand an internal explosion and prevent ignition of the surrounding atmosphere. IIB covers gas groups such as ethylene, propane, and town gas. T4 means the maximum surface temperature does not exceed 135 °C, making it safe for environments with auto‑ignition temperatures above this level. This certification is essential for installation in Zone 1/Zone 2 hazardous areas.

Q3: Can this instrument handle liquefied gases?

A: Yes. The built‑in vaporization chamber heats the sample to 40 °C, ensuring complete gasification of liquefied gases (e.g., LPG, refrigerant gases) before they reach the sensor. This prevents liquid carryover that could damage the electrolytic cell.

Q4: How far can the RS‑485 signal travel?

A: RS‑485 communication can extend up to 1,200 meters (≈100 meters as noted in marketing materials, but technically up to 1.2 km with proper cabling). For longer distances, the professional monitor software supports networking of more than 100 meters of distributed analyzers from a single PC, enabling plant‑wide moisture monitoring.

Q5: What is the advantage of the electrolytic method for acid gases?

A: Most industrial moisture analyzers (capacitive, chilled mirror) use materials that degrade when exposed to acidic gases like H₂S, SO₂, or HCl. The P₂O₅ electrolytic sensor is chemically resistant to these environments, making it the preferred choice for sour gas, sulfur recovery, and acid gas injection applications.

Q6: How is the sensor protected from over‑range conditions?

A: The analyzer includes an automatic over‑range protection circuit that detects excessive gas pressure or abnormally high moisture levels and temporarily isolates or bypasses the sensor to prevent saturation or physical damage. An alarm is triggered to alert operators.

Q7: Can the analyzer be powered by DC voltage?

A: Yes. The instrument supports dual power options: AC 220/110V (50/60 Hz) for standard installations, or DC 24V for remote sites, solar‑powered systems, or integration with plant DC backup supplies.

Function:
Perform on-line measurement of the dew point of non-corrosive gas and acid gas, or trace water content in the gas.
Principle:
The coil-like double platinum wire and its gap (less than 20um) constitute an electrolytic cell. Phosphorus pentoxide in the gap between platinum wires absorbs trace water to produce phosphoric acid and generates a weak current. The current is proportional to the amount of water absorbed. The dew point or trace water content is calculated according to the measured current.
Standards：GBT 5832.1
Characteristics:
- High precision, 10 ppb.
- Wide Test range, -80℃Td~-6 ℃Td.
- Corrosion resistance - It can measure acid gas and slightly corrosive gas.
- The gasification chamber is used to heat the liquefied gas.
- Sensor safety - with a sensor over range protection function.
- Meter net - more than 100 meters can be monitored by a computer.
- Explosion-proof class, ExdIIBT4.
- With constant temperature function, it can be used stably under various climate conditions.
- Provide an RS-485 port to connect to a computer.
- Professional Monitor software - sample data showed in curve form, stored in the database. Real-time device control.

Specification:

Name	Parameter	Name	Parameter
Dew point Range	-90 ℃Td ～ -6 ℃Td	Repeatability	≤±1 ℃Td
Water content range	0.1 ppmv～3800 ppmv	precision	0.1 ppmv或1% m.v.
Flow rate	100 sccm (adjustable)	Response time	＜5 min
Gasification Temp.	40℃	Protection level	IP65
Communication	RS 485	Explosion-proof class	EXDIIBT4
connector	1/8”meter pipe	Gas pressure	≤1MPa
Size	300Ⅹ120Ⅹ360 mm (LⅩBⅩH)	Power supply	AC220/110V 50/60Hz or DC24V
Environment	-30 ℃ ～ 50 ℃

Keywords:

Portable Professional Dew Point Meter

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