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ATEX Pump

ATEX Pump
Selection Criteria

Zone and category determination, fluid properties, explosion group matching, material conductivity and sealing: 7-step systematic selection guide.

  • 7 Criteria
  • Fluid Analysis
  • Explosion Group
  • Material Selection

7-Step Selection Methodology

How to Perform Systematic ATEX Pump
Selection?

ATEX pump selection is not random product research; it requires sequential evaluation of seven interconnected criteria beginning from the site's hazard class and ending with total cost of ownership, constituting an engineering process. Skipping or misclassifying even a single criterion can lead to accidents that threaten human safety and serious legal and financial liability from regulatory violations.

The process always begins with correct determination of zone and category; no decision about pump model, motor class, or material selection can be made without this determination. After zone and category are established, the physical and chemical properties of the fluid are analyzed in depth; parameters such as viscosity, density, chemical aggressiveness, and solid content directly affect both pump type and material selection.

Explosion group matching is the most technical step of the criteria: the gas or vapor present on site must be classified into IIA/IIB/IIC gas group and T class calculation must be performed. When this matching is done incorrectly, a seemingly certified pump may not actually meet the site's ignition energy. The seven steps, completed with material conductivity, sealing design, grounding, and TCO evaluation, create a universal selection framework applicable across all scales of ATEX site.

  • No decision can be made about pump model, motor, or material without determining zone and category
  • The viscosity, chemical aggressiveness, and solid content of the fluid directly determine both the pump type and material
  • Incorrect matching of gas group (IIA/IIB/IIC) renders a certified pump actually unsafe
  • Use of non-conductive plastic material creates ATEX violation through static electricity accumulation
  • TCO analysis demonstrates that the initial cost of ATEX pump is competitive in the long term

Selection Criteria

7 Fundamental Criteria in ATEX Pump Selection

Criterion 1 — Zone and Category Determination

Zone classification defines how frequently an explosive atmosphere occurs: Zone 0 (continuous), Zone 1 (occasional), Zone 2 (rarely). For each zone, the ATEX category of pump components is determined; Zone 0 → Category 1G, Zone 1 → Category 2G, Zone 2 → Category 3G. The end user is legally responsible for determining zone boundaries within the framework of IEC 60079-10-1 standard and preparing area classification documents (DSEAR Risk Assessment); without these documents, ATEX equipment selection remains unfounded.

Criterion 2 — Analysis of Fluid Properties

Six fundamental parameters related to the fluid to be conveyed must be evaluated systematically: viscosity (in cP at 20 °C and operating temperature), density (kg/m³), chemical aggressiveness (pH, solvent power, concentration), solid content (% by mass and maximum particle size), operating temperature, and vapor pressure. Vapor pressure particularly affects cavitation risk and gas group T class calculation; in high vapor pressure fluids, surface temperature limitation may require a stricter T class.

Criterion 3 — Explosion Group and T Class Matching

Determining the gas group is based on the minimum ignition energy and maximum experimental safety gap (MESG) of the gas or vapor that may form in the field. IIA (propane, methanol, acetone, butane) represents the lowest risk group; IIB (ethylene, diethyl ether, hydrogen sulfide) medium risk; IIC (hydrogen, acetylene) highest risk — each group encompasses the previous one, meaning an IIC certified pump can be used in all groups. T class limits the maximum surface temperature of the pump: a safety margin of at least 80% of the fluid's ignition temperature is required.

Criterion 4 — Material Selection and Conductivity

In ATEX environments, pump materials are evaluated on two aspects: chemical resistance and electrical conductivity. Stainless steel 316L offers broad chemical compatibility and good conductivity; cast iron is strong in mechanical strength but unsuitable for corrosive environments. Carbon-filled PP and PVDF provide adequate conductivity (≤10⁶ Ω) along with chemical resistance; unfilled standard PP or PE are non-conductive and are not considered ATEX compliant. PTFE-lined versions maximize chemical resistance but require special attention in grounding design.

Criterion 5 — Sealing Design

Fluid leakage from the pump casing can become a direct ignition source in an ATEX environment; therefore, sealing design is an integral part of pump selection. Single mechanical seal is sufficient for low-risk applications, while in Zone 0 and Zone 1 with explosive fluids, double mechanical seal (with pressurized barrier fluid) is preferred. Magnetically driven pumps eliminate the mechanical seal entirely, making leakage structurally impossible. AODD diaphragm pumps have a natural advantage in this criterion since they do not contain mechanical seals.

Criterion 6 — Grounding and Static Electricity Control

Static electricity accumulation, particularly in low-conductivity fluids and plastic components, becomes a serious ignition source. EN 60079-32-1 standard defines engineering requirements for static control in ATEX equipment: all conductive components must have grounding connection points, connections must be documented with measurement protocol, and periodic conductivity tests must be performed. Ensuring continuity between pump casing, pipe connections, flanges, and filter housings is mandatory for each installation; this documentation is routinely required in ATEX inspections.

Criterion 7 — Total Cost of Ownership (TCO)

The initial purchase cost of an ATEX pump can be 30–80% higher than standard pumps; however, this difference typically closes within 2–4 years. Reduced failure frequency, longer maintenance intervals, elimination of product losses from leakage, and prevention of penalties and legal costs arising from workplace safety incidents play a decisive role in TCO calculation. Particularly in facilities processing expensive solvents or toxic chemicals, the contribution of a leakage-free ATEX pump is measurable not only as safety but also as direct economic return.

Reference Tables

Gas Group and Material
Selection Table

Gas Group Example Gases / Vapors Risk Level Required ATEX Code
IIA Propane, methanol, acetone, butane, ethanol, ammonia Low — wide ignition range Ex II 2G IIA T3/T4
IIB Ethylene, diethyl ether, hydrogen sulfide (H₂S), sulfur dioxide Medium — low ignition energy Ex II 2G IIB T3/T4
IIC Hydrogen (H₂), acetylene, carbon disulfide High — very low ignition energy Ex II 1G IIC T6

Frequently Asked Questions

ATEX Pump Selection Criteria
Frequently Asked Questions

Zone classification is the legal responsibility of the end user (facility owner). In accordance with the ATEX Employer Directive (1999/92/EC) in the EU and equivalent legislation in Turkey, the facility owner is required to prepare a DSEAR Risk Assessment or equivalent explosive atmosphere risk evaluation and document zone boundaries in writing. Without these documents, ATEX equipment selection loses legal validity and serious sanctions may be encountered during inspections.
No, it cannot be used. Gas group certification is not cumulative but layered; an IIA-certified pump is only safe in an IIA environment. Since an IIB environment requires lower ignition energy, IIA equipment cannot provide adequate protection. An IIC-certified pump, on the other hand, covers all groups (IIA, IIB, IIC); therefore, IIC certification is technically preferable, especially in facilities where multiple gas types may be present.
Unfilled polypropylene (PP) and polyethylene (PE) are electrically insulating materials; their surface resistances typically measure in the 10¹²–10¹⁴ Ω range. This high resistance permits static electricity accumulation on the pump surface. In an explosive atmosphere, the discharge of accumulated static charge can create a spark; this spark serves as an ignition source. PP/PVDF with carbon black or conductive fiber additives, however, exceeds the conductivity threshold at ≤10⁶ Ω surface resistance and is considered ATEX compliant.
T class limits the maximum temperature that the pump surface can reach under normal operating conditions. The rule is: the pump surface temperature must not exceed at least 80% of the ignition temperature of the flammable substance in the environment; in practical application, a 20% safety margin must be left regardless of temperature. For example, for a gas with an ignition temperature of 300 °C, a maximum surface temperature of 240 °C is targeted; this value corresponds to T2 class (300 °C), not T3 class (200 °C). A higher T class number means more restrictive: T6 is the most restrictive (85 °C), T1 offers the widest tolerance (450 °C).
Magnetic drive (mag-drive) pumps should be the preferred choice in Zone 0 and Zone 1 applications where toxic, corrosive, or high-value fluids are handled, when dual mechanical seals are insufficient, or when zero leakage tolerance is required. Additionally, in critical processes where frequent maintenance cannot be performed, it reduces operating costs by eliminating the need for seal replacement. However, in high-viscosity fluids and fluids with solid content, magnetic coupling wear may occur; engineering evaluation is required in these cases.
The TCO calculation for an ATEX pump should cover five main items: (1) Initial purchase and installation cost — including ATEX-certified motor, grounding equipment, and ATEX-compatible accessories. (2) Annual maintenance cost — seal, gasket, spare parts, and maintenance labor. (3) Energy consumption — annual electricity bill depending on pump efficiency. (4) Downtime cost — production losses due to failure or maintenance. (5) Risk cost — potential accident, fines, insurance increase, and legal liability. As a general rule, the 5-year TCO of an ATEX pump often turns out lower than that of a standard pump due to frequent downtime and high risk costs.

Selection Criteria Consulting

The Right ATEX Pump for Your Field
Let's Choose Together

Share your Zone class, fluid properties, gas group, and T class information; by applying the 7-step selection methodology to your field, let's determine the most suitable ATEX pump solution together.

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