The nitrogen foam delivery system is an alternative emergency depopulation system that uses high expansion water based foam bubbles to deliver nitrogen gas into a container, trailer, coral or barn. The integrity of the foam structure allows a blanket of foam to be maintained over the animal which is then exposed to, and maintained in anoxic conditions, effectively zero oxygen, until dead. The mode of death is intended to be by exposure to gas, not by the occlusion of the airway by the foam bubbles. Collaborative trials between the UK and US, to validate this process have been delayed by the exceptional circumstances we have found ourselves in over the past 12 months.

The system is made up from modular units which hold five key components:

  1. Individual foam generator units
  2. Control and distribution platform
  3. Water supply
  4. Liquid nitrogen supply
  5. Gas Vaporiser.

Water supply, liquid nitrogen supply and vaporiser are all elements that can be accessed from industrial suppliers at the time of a deployment operation therefore do not require capital investment nor additional maintenance requirement. The remaining components are incorporated onto a platform base in a shipping container which meets international standards for shipping and transport. Irrespective of the scale of the operation or deployment situation, there are several elements of the system that will be common to all situations. This core platform, built into the shipping container, houses a monitoring and control system to measure and record flow rates, pressures and temperatures of the gas and liquid supplies and can control the relative flows to ensure the correct delivery and rate and expansion ratio of the finished foam. The distribution pipe work manifold allows the connection of foam generator units and their respective gas and foam solutions hose supplies

The shipping container also holds 12 foam generators, supply hoses, the gantry support system and all ancillary equipment. The system provides for multiple deployment options whether on poultry or pig farms. A temporary gantry is assembled in front of the barn approximately 20ft high and span at least 10ft wide. Two foam generators and the associated supply hoses are suspended centrally from the gantry, above the parked trailer. An open-topped trailer is backed up to the loading ramp and loaded with a single deck of pigs following industry standard operating procedures for the handling of swine.

The use of nitrogen-filled water-based foam is a feasible solution for emergency depopulation of swine. It allows for the use of an alternative gas where carbon dioxide gas has been in short supply. The system has been designed for rapid deployment with a small number of operators.
Standard operating procedures have been developed to allow the system to be used on smaller farms or on centralized sites to service a local area. It can be deployed and set up in a few hours, with the potential to depopulate over 8000 market-weight pigs per day.

Key Findings:

  • The systems was readily adapted to deliver short 2 minute bursts of high expansion gas-filled foam bubbles into a coral
  • In pre-deployment trials the average rate of delivery of finished foam with 2 foam generators was 3101 cuft per minute.