Introduction
Hydrogen is the simplest and smallest atomic element. Water, acids, bases, and the immense family of organic compounds all contain hydrogen. Even though hydrogen is not corrosive, it can cause problems for pressure transmitters through Hydrogen Permeation.
Hydrogen Permeation
Hydrogen Permeation is the penetration of hydrogen ions through the thin metal isolation diaphragms of a pressure transmitter. Over time, this penetration will cause errors in measurement. Hydrogen is normally found in nature in a diatomic state (a H2 molecule). In this state, hydrogen cannot penetrate the thin (0.001 inch to 0.002 inch thick) isolation diaphragms because the H2 molecule does not have enough energy, due to its size, to push through the lattice structure of the metal isolation diaphragm. However, if the hydrogen molecule splits into two hydrogen ions (H+), then, due to its reduced size, the H+ ion can draw enough energy from the process to push its way through this lattice structure.
Once on the other side of the isolation diaphragm, the H+ ion will reform H2 molecules with other H+ ions that have also passed through. The H2 molecules become trapped inside the fill fluid of the transmitter because they are once again too large to pass back through the isolation diaphragm. Gradually, the H2 molecules will dissolve into the fill fluid. Over time the fill fluid will become saturated and a hydrogen bubble will form.
This hydrogen bubble will cause zero and span shifts, degrading the performance of the pressure transmitter.
In extreme cases, the hydrogen bubble can build up enough volume to force the isolation diaphragm to expand outward causing cracking of the isolation diaphragm. This phenomenon is known as "Jiffy-Pop". These cracks will lead to leakage of the fill fluid into the process and the complete failure of the pressure transmitter.
Examples of Problem Processes
A pure hydrogen service is an obvious application in which hydrogen permeation could be present. However, hydrogen permeation can occur in applications where hydrogen is not in its pure form.
Example #1
In a pure hydrogen service, hydrogen permeation is caused by kinetic energy. When the process is at high temperature or at high pressure, hydrogen molecules collide with each other releasing kinetic energy. This kinetic energy breaks the bonds of the hydrogen molecules, yielding hydrogen ions.
H2 → 2H+
Example #2
Hydrogen permeation can be caused by galvanic energy. Galvanic energy is an electrolytic reaction between two dissimilar metals. For example, processes with sea water (a weak electrolyte) and zinc-plated impulse piping will generate galvanic energy through corrosion. This galvanic energy breaks the bonds of the molecules containing hydrogen (in this example, water), yielding hydrogen ions.
H2O → H+ + OH−
Solutions
Picking the correct isolation diaphragm material can reduce the rate of hydrogen permeation. The tighter the lattice structure of the material, the more resistance there is to permeation. Historically, stainless steel has been the material of choice for general permeation protection. Although, nickel based materials like Hastelloy C-276 and Monel offer greater corrosion protection than stainless steel, they were avoided due to their "loose" lattice structure.
For critical applications, gold-plated stainless steel diaphragms yield the best resistance to permeation. The gold plating adds a thin layer of very tight lattice structure to the stainless steel diaphragm. This is the tightest lattice structure a transmitter diaphragm can have.
Yokogawa Solutions
Yokogawa offers several options to improve the corrosion and permeation resistance of our pressure transmitters.
Yokogawa Solution #1
EJA and EJX series pressure transmitters come standard the Hastelloy C-276 diaphragm with a Cr-oxide passivated layer. ("S" material code) This passivated layer adds a tight lattice structure to the diaphragm. The passivated Hastelloy C-276 gives similar permeation resistance as stainless steel; but, outperforms stainless steel due to its better corrosion resistance, yielding longer service life.
Yokogawa Solution #2
The permeation resistance of a gold-plated diaphragm is more than 5 times better than the permeation resistance of passivated Hastelloy C-276. The EJA and EJX series pressure transmitters offer gold-plated options on both the transmitter diaphragm and the remote seal diaphragms.
The transmitters offer gold-plated Hastelloy C-276 isolation diaphragms (Option code /A1). Since the diaphragm is internal and therefore protected from the potential of physical damage, the gold is plated onto the process side of the isolation diaphragm.
The remote seals offer gold-plated 316 Stainless Steel or gold- plated Hastelloy C-276. (Option code /A1) Since the remote seal isolation diaphragm is exposed, the gold is plated on the fill fluid side of the diaphragm.
Conclusion
Appropriate material selection of the transmitter's isolation diaphragms is the important key in protecting a transmitter from hydrogen permeation. The selection of the material is the customer's responsibility. If there is any doubt about the level of risk of hydrogen permeation in a process, select Yokogawa's Solution #2 (Gold-plated diaphragm).
| Isolation Diaphragm | ||||
|---|---|---|---|---|
| Passivated Hastelloy C‑276 | Gold‐Plated Hastelloy C‑276 | Gold‐Plated 316 SST (Remote Seal) | Gold‐Plated Hastelloy C‑276 (Remote Seal) | |
| EJA110A | ✓ | ✓ | ||
| EJA118A | ✓ | ✓ | ||
| EJA130A | ✓ | ✓ | ||
| EJA430A | ✓ | ✓ | ||
| EJA438A | ✓ | ✓ | ||
| EJA310A | ✓ | ✓ | ||
| EJA510A | ✓ | ✓ | ||
| EJA530A | ✓ | ✓ | ||
| EJX110A | ✓ | ✓ | ||
| EJX118A | ✓ | ✓ | ||
| EJX130A | ✓ | ✓ | ||
| EJX430A | ✓ | ✓ | ||
| EJX438A | ✓ | ✓ | ||
| EJX310A | ✓ | ✓ | ||
| EJX510A | ✓ | ✓ | ||
| EJX530A | ✓ | ✓ | ||
| Process Fluid | Material Piping | |||
|---|---|---|---|---|
| Zinc-Plated | Brass | Iron | Stainless Steel | |
| Pure Water | S | S | S | S |
| Boiler Feeding Water | S | S | S | S |
| Tap Water | S | S | S | S |
| Well Water (without Sea Water) | Δ | S | S | S |
| Water for Industrial Use | Δ | Δ | S | S |
| Waste Water (without Sea Water) | Δ | Δ | Δ | S |
| Sea Water | /A1 | /A1 | /A1 | S |
S: Passivated Hastelloy C ‐ 276 can be used
Δ: Depends on process conditions
/A1: Gold ‐ plated Diaphragm recommended
Industries
-
Base Chemical
Yokogawa has been serving the bulk chemical market globally and is the recognized leader in this market. With products, solutions, and industry expertise, Yokogawa understands your market and production needs and will work with you to provide a reliable, and cost effective solution through the lifecycle of your plant.
-
Chemical
Chemical plants rely on continuous and batch production processes, each posing different requirements for a control system. A continuous process calls for a robust and stable control system that will not fail and cause the shutdown of a production line, whereas the emphasis with a batch process is on having a control system that allows great flexibility in making adjustments to formulas, procedures, and the like. Both kinds of systems need to be managed in available quality history of product, and to be able to execute non-routine operations. With its extensive product portfolio, experienced systems engineers, and global sales and service network, Yokogawa has a solution for every plant process.
-
Water & Wastewater
Water resources are finite, and therefore contributing to a sustainable water cycle is one of the Sustainable Development Goals (SDGs). Yokogawa has been providing advanced digital control solutions for the stable supply of clean and safe water, wastewater treatment for protecting the water environment, water loss management and optimization of plant operation for reducing CO2 emissions and running costs. With our leading-edge technologies, dependable products and extensive expertise and experience of diverse water projects around the world, we work with you to provide sustainable water solutions that boost your business and add value throughout the plant lifecycle.
Yokogawa supports a wide range of water control applications in both the municipal and industrial water markets.
Related Products & Solutions
-
EJA110A
Traditional-mount Differential Pressure Transmitter based on the EJA-A Series.
-
EJA118
Differential Pressure Transmitter with Remote Diaphragm Seals based on the EJA-A Series.
-
EJA130A
Traditional-mount High-static Differential Pressure Transmitter based on the EJA-A Series.
-
EJA210E
Standard Flange-mounted Differential Pressure Transmitter designed for Liquid-level applications based on the EJA-E series.
-
EJA310A
Traditional-mount Absolute Pressure Transmitter based on the EJA-A Series.
-
EJA310E
Standard Traditional-mount Absolute Pressure Transmitter based on the EJA-E Series.
-
EJA430A
Traditional-mount Gauge Pressure Transmitter based on the EJA-A Series.
-
EJA430E
Traditional-mount Gauge Pressure Transmitter based on the EJA-E series.
-
EJA438
Gauge Pressure Transmitter with Remote Diaphragm Seal based on the EJA-A Series.
-
EJA438E
Standard Gauge Pressure Transmitter with Remote Diaphragm Seal based on the EJA-E Series.
-
EJA440A
Traditional-mount High Gauge Pressure Transmitter based on the EJA-A Series.
-
EJA440E
Standard Traditional-mount High Gauge Pressure Transmitter based on the EJA-E Series.
-
EJA510E
Standard In-Line Mount Absolute Pressure Transmitter based on the EJA-E Series.
-
EJA530A
In-Line Mount Gauge Pressure Transmitter based on the EJA-A Series.
-
EJA530E
In-Line Mount Gauge Pressure Transmitter based on the EJA-E Series.
-
EJX110A
Traditional-mount Differential Pressure Transmitter based on the EJX-A Series.
-
EJX110B Wireless Differential Pressure Transmitter
The high performance wireless differential pressure transmitter EJX110B features a single crystal silicon resonant sensor and is suitable to measure liquid, gas, or steam flow as well as liquid level, density, and pressure.
-
EJX115A
Differential Pressure Transmitter attached to an IFO assembly based on the EJX-A Series as a high performance model.
-
EJX118A
Differential Pressure Transmitter with Remote Diaphragm Seals based on the EJX-A Series as a high performance model.
-
EJX118B Wireless Differential Pressure Transmitter with Remote Diaphragm Seals
Wireless diaphragm seals are used to prevent process medium from entering directly into the pressure-sensing assembly of the differential pressure and pressure transmitters, they are connected to the transmitter using capillaries filled with fill fluid.
-
EJX120A
Traditional-mount Differential Pressure Transmitter designed for Draft Range applications based on the EJX-A Series as a high performance model.
-
EJX130A
Traditional-mount High Static Differential Pressure Transmitter based on the EJX-A Series as a high performance model.
-
EJX210A
Flanged-mounted Differential Pressure Transmitter designed for Liquid-level applications based on the EJX-A Series as a high performance model.
-
EJX210B Wireless Flange Mounted Differential Pressure Transmitter
The high performance wireless flange mounted differential pressure transmitter EJX210B features a single crystal silicon resonant sensor and is suitable to measure levels of densities of solidifying or precipitating liquids.
-
EJX310A
Traditional-mount Absolute Pressure Transmitter based on the EJX-A Series as a high performance model.
-
EJX310B Wireless Absolute Pressure Transmitter
The high performance wireless pressure transmitter EJX310B features a single crystal silicon resonant sensor and are suitable to measure liquid, gas, or steam flow as well as liquid level, density, and pressure.
-
EJX430A
Traditional-mount Gauge Pressure Transmitter based on the EJX-A Series.
-
EJX430B Wireless Gauge Pressure Transmitter
The high performance wireless guage pressure transmitter EJX430B features a single crystal silicon resonant sensor and are suitable to measure liquid, gas, or steam flow as well as liquid level, density, and pressure.
-
EJX438A
Gauge Pressure Transmitter with a Remote Diaphragm Seal based on the EJX-A Series as a high performance model.
-
EJX438B Wireless Gauge Pressure Transmitter with Remote Diaphragm Seals
Wireless diaphragm seals are used to prevent process medium from entering directly into the pressure-sensing assembly of the differential pressure and pressure transmitters, they are connected to the transmitter using capillaries filled with fill fluid.
-
EJX440A
Traditional-mount High Gauge Pressure Transmitter based on the EJX-A Series as a high performance model.
-
EJX510A
In-Line Mount Absolute Pressure Transmitter based on the EJX-A Series as a high performance model.
-
EJX510B Wireless In-Line Mount Absolute Pressure Transmitter
The high performance wireless absolute and gauge pressure transmitters EJX510B and EJX530B feature single crystal silicon resonant sensor and are suitable to measure liquid, gas, or steam pressure.
-
EJX530A
In-Line Gauge Pressure Transmitter based on the EJX-A Series.
-
EJX530B Wireless In-Line Mount Gauge Pressure Transmitter
The high performance wireless absolute and gauge pressure transmitters EJX510B and EJX530B feature single crystal silicon resonant sensor and are suitable to measure liquid, gas, or steam pressure.
-
EJX610A
High Performance In-Line Mount Absolute Pressure Transmitter based on the EJX-A Series.
-
EJX630A
In-Line Mount High Performance Gauge Pressure Transmitter based on the EJX-A Series.
-
EJX910A
This transmitter precisely measures differential pressure, static pressure, and process temperature; then uses these values in a high-perfomance on-board flow computer to deliver fully compensated Mass Flow.
-
EJX930A
Designed specifically for high static pressure applications, this transmitter precisely measures differential pressure, static pressure, and process temperature; then uses these values in a high-perfomance on-board flow computer to deliver fully compensated Mass Flow.
-
Pressure Transmitters
The accurate and stable measurement of process pressure with Yokogawa Pressure Transmitters supports the safe, reliable, and profitable operation of your plant.