Recommendations

Handling Operations

Product sampling

Product sampling is a potential source of personnel exposure to 2-EHN. Design and procedures should be developed to minimize personnel and environment exposure to 2-EHN.

Product handling: loading, unloading, pumping

Product handling is a potential source of personnel exposure to 2-EHN. Design and procedures should be developed to minimize personnel and environment exposure to 2-EHN.

  • Loading
    Use a dedicated loading arm. Control static electricity. If a multi-compartment tank wagon is loaded, ensure 2-EHN is not shipped adjacent to heated cargoes. Ensure proper electrical grounding and electrical continuity in all facilities.
  • Unloading
    Use a dedicated hose. Control static electricity. Avoid manifolds to prevent accidental ingress of 2-EHN into heated lines.
  •  Pumping
    2-EHN is a self-reactive substance. In the absence of air, it can decompose in the bulk liquid phase if heated. This occurs most commonly under pressure in a blocked or dead-headed pump, or other sealed systems, and can lead to violent bursting of the equipment. The principle here is to use equipment that does not have the potential to heat the product. Pumped transfer of 2-EHN should always be done under controlled conditions, and all transfer valves must be opened before pumps are started. Do not pump 2-EHN against a closed outlet: this may heat the product within the pump, depending on the type of the pump.Pneumatically powered diaphragm pumps provide an inherently safe and reliable means of pumping 2-EHN.Centrifugal pumps are not as inherently safe as pneumatic diaphragm pumps for 2-EHN service. In any case, extra control systems are required.Gear pumps and other positive displacement systems can heat 2-EHN rapidly when the pump outlet is closed or blocked. Consequently, their use is not recommended.Safety pump trip controls and instrumentation must be fitted with:

    • A temperature trip set to stop the pump at a product temperature of 50-60°C.
      In exceptional circumstances, specific operations may require a higher temperature trip set up to a maximum of 75°C, subject to detailed expert risk assessment in conjunction with your supplier.
    • A pressure switch to stop the pump if the outlet is blocked or closed; and/or
    • A low flow switch to stop the pump if the outlet is blocked or closed.

    To prevent the risk of heating the product, closed circuit pumping must be avoided, including that through pressure relief valves when the pump outlet is closed or blocked.

    The majority of incidents involving 2-EHN have been due to overheating of pumps, resulting in bursting of the equipment. Therefore, careful consideration of the siting of pumps needs to be made, and the consequences of pump failure fully assessed.

Tank to tank transfer

Tank to tank transfer of 2-EHN can be safely carried out with nitrogen or air padding, while using a pneumatic driven pumping system or pumps as described above.

Equipment clean-up

Inadequate cleaning of equipment or pipe work introduces a risk of environmental contamination and a higher potential for decomposition of 2-EHN residues.

A specific procedure should be developed by skilled personnel, that describes health and environmental hazards, as well as temperature limits, to ensure that cleaning operations are conducted in an effective and safe manner.