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Explosion Proof Pumps | ATEX & Class I Div 1 Guide | ISS
The explosion-proof pump design prevents internal or external explosions by enclosing parts that could ignite either the transfer substance or the surrounding atmosphere. The Intrinsically Safe Store provides explosion-proof pumps for use in hazardous atmospheres.
Types of Pumps
Explosion-proof pumps operate on either a dynamic or positive displacement design.
The dynamic pump type uses the momentum and velocity of the fluid to generate pumping pressure. Furthermore, the pump type works well with varying flow requirements and low viscosity material. Dynamic explosion-proof pumps, like centrifugal pumps, can deliver a high flow rate in hazardous areas.
Positive displacement explosion-proof pumps use changes in cavity volume to transfer material. Thus, the positive displacement type is well suited for applications requiring a constant flow at high pressure with relatively low flow rates. This type of explosion-proof pump is ideal for hazardous areas with high viscosity fluids.
There’s a risk of an explosion whenever you’re pumping liquid out of a Hazardous facility. And, depending on the type of fluid transported out of the area, there is a significant threat to safety.
Explosion Proof Class and Division
Class II, Division 2, or Class III, Divisions 1 or 2 locations use dust-tight specifications. Whereas Class I, Divisions 1 or 2 areas use Explosion-Proof designs. Qualification for Division 1 meets Division 2 requirements.
Constructing a pump is not enough to rate for “Explosion-Proof.” A third party must approve the pump for use in explosive environments. For example, two of the more common agencies are Factory Mutual Insurance (FM) for wastewater and industrial applications and the Mine Safety and Health Administration (MSHA) for the mining, metals, and aggregate industry. For FM, there are different types of approval depending on the specific application requirements.
Class 1: Flammable gasses and vapors are present leading to a potential risk.
Division 1 signifies Hazardous materials are present under normal operating conditions. Additionally, Division 2 means gasses present an upset scenario.
Group C and D: These refer to specific gasses for which the pump or motor are rated.
Sealing Design: Why It Matters for Hazardous Fluid Transfer
Beyond the motor’s explosion-proof rating, the pump’s shaft sealing method is a separate safety consideration when the fluid itself is flammable or hazardous. A conventional mechanical seal has some inherent risk of leakage at the shaft penetration over its service life. Magnetically-coupled (seal-less) pump designs eliminate this shaft penetration entirely by transmitting drive torque through a magnetic field across a sealed containment shell, removing the leak path at its source. For highly hazardous or toxic fluids, a seal-less design is often specified in addition to (not instead of) the pump’s Class/Division or Zone rating for the motor and enclosure.
Material Compatibility
An explosion-proof rating addresses ignition risk from the motor and electrical components — it does not address chemical compatibility between the pumped fluid and the pump’s wetted materials (housing, impeller, seals). Selecting wetted materials — commonly stainless steel, PVDF, or PTFE-lined construction depending on the fluid — that resist corrosion or degradation from the specific chemical being transferred is a separate part of the specification process, alongside the hazardous-area rating.
FAQs About Explosion Proof Pumps
Is an explosion-proof pump the same as an intrinsically safe pump?
No. Explosion-proof (flameproof) construction contains a potential internal ignition within the motor enclosure, which suits the higher power draw typical of pump motors. Intrinsic safety instead limits circuit energy below ignition levels and is more commonly applied to low-power instrumentation and control circuits rather than motor-driven equipment like pumps.
Can a Division 1-rated pump be used in a Division 2 location?
Yes. Per NEC Article 500, equipment rated for Division 1 meets the requirements for Division 2, since Division 1 covers the more demanding condition of hazardous materials being present under normal operating conditions.
Does the pump’s gas group rating need to match the specific chemical being pumped?
The motor’s Group rating (e.g., Group C and D) reflects the ignition characteristics of the vapors or gases that could be present in the surrounding atmosphere where the pump operates, which is a related but distinct question from the pump’s wetted-material compatibility with the fluid being transferred. Both need to be confirmed against the specific site and application.