An AODD pump moving flammable solvent through a non-conductive plastic casing generates static charge. The fluid moves at velocity, contacts non-conductive surfaces, and charge accumulates — on the fluid, on the pump body, on the connected hose. If the pump isn’t grounded, that charge has nowhere to dissipate. It builds until it discharges. In the presence of flammable vapour, that discharge is an ignition event.
This is not a theoretical risk. It is the mechanism behind real solvent fires in process plants, and it’s why the Fluimac Phoenix manual treats grounding as a hard requirement, not optional practice. The manual states directly that incorrect or absent grounding voids ATEX certification. The pump is no longer compliant, regardless of what the nameplate says.
How Static Charge Builds in a Pump
Charge generation in fluid handling is called triboelectric charging. When a fluid flows across a surface — especially a non-conductive surface like PP or PVDF — electrons transfer between the fluid molecules and the surface. This creates a charge separation. In conductive systems (metal pipes, metal pump bodies, properly grounded), the charge dissipates continuously through the electrical path to earth. In non-conductive systems without grounding, it accumulates.
AODD pumps are particularly prone to static generation because of the pulsating, high-velocity fluid flow through the check valve ports and manifolds. Each stroke pushes fluid at relatively high velocity through tight passages. Hydrocarbons, solvents, and low-conductivity fluids are especially high-risk because they don’t self-dissipate charge the way conductive fluids (water, acids) do.
Grounding Requirements for the Phoenix
The Fluimac Phoenix must be connected to a dedicated earth point before any operation with flammable fluids. The manual specifies that the grounding connection must be made to the pump’s designated earth terminal — not to adjacent pipework, not to the frame the pump sits on, not to a general equipment ground that may or may not have continuity to true earth.
The earth connection must be verified with a continuity tester before commissioning. A visual connection is not sufficient — a corroded terminal, a loose lug, or a broken conductor inside an intact sheath can all create a ground path that appears connected but has no actual continuity.
For ATEX Zone 1 installations, grounding must be rechecked as part of regular maintenance. The Phoenix manual identifies loss of grounding as a condition that requires immediate pump shutdown — it is a safety-critical fault, not a maintenance item.
Conductive Casing Variants
Standard PP and PVDF pump casings are electrically non-conductive. For applications where static dissipation through the casing itself is required, Fluimac offers conductive-grade casing variants: PC (PP + carbon fibre) and KC (PVDF + carbon fibre). These materials have sufficient electrical conductivity to dissipate surface charge to the grounded pump structure, rather than allowing charge to accumulate on the casing exterior.
The conductive variants are typically specified for ATEX Zone 1 applications involving low-conductivity hydrocarbons, or where regulatory requirements mandate conductive wetted materials regardless of zone. They carry essentially the same chemical resistance as standard PP and PVDF but provide the static dissipation path that non-conductive grades cannot.
The Hose and Pipe Ground Loop
Grounding the pump body alone is not complete protection if the connected hose and pipework are non-conductive and ungrounded. Charge can accumulate on the fluid inside an ungrounded hose section and discharge at a fitting or valve — remote from the pump but still within the hazardous area. For flammable fluid applications, the entire fluid circuit should be reviewed for grounding continuity: pump, hose, valves, receiving vessel. Conductive hose with grounded end fittings is standard practice in solvent handling.
What Happens Without Grounding
Without grounding, accumulated charge eventually reaches a discharge threshold. The discharge is an electrostatic spark — low energy relative to many ignition sources, but more than enough to ignite most solvent vapours. The minimum ignition energy (MIE) for common solvents like acetone, toluene, or MEK ranges from 0.2 to 1.4 mJ. Electrostatic sparks from ungrounded equipment regularly exceed this threshold.
The spark doesn’t have to occur at the pump itself. Charge builds on the fluid in motion and can discharge wherever the fluid contacts an earthed surface — including the inside of a receiving vessel or tank. This makes the hazard difficult to anticipate without systematic grounding of the entire system.
If you’re specifying a Fluimac Phoenix for flammable or static-sensitive applications and need guidance on grounding requirements and casing selection, contact us at info@autoflotechnology.com.