2″ NPS/BSP Male IBC Pressure & Vacuum Relief Vent
Part No: HMVMN20MM027
CPP® dual-function IBC vent designed to provide both vacuum relief during discharge and pressure relief when internal pressure rises.
Specification
- Connection: 2″ male
- Thread: BCS G2 × 11.5
- Compatibility: designed for compatible 2″ BSP / NPS IBC vent connections
- Body material: glass-filled polypropylene
- Seal material: PP-based elastomer
- Spring: 316 stainless steel
- Function: pressure relief and anti-vacuum / vacuum relief
- Approximate vacuum air-in flow: around 100 L/min
Important flow limitation
HMVMN20MM027 is a low-flow vent and is not intended to support rapid continuous emptying of a full 1,000 L IBC.
The vent allows approximately 100 L/min of replacement air. When decanting, the liquid discharge rate must not exceed the vent's ability to admit air. For higher-rate gravity discharge, pause the flow after approximately 100–200 litres to allow the container to recover before continuing.
This is especially important with many newer IBC bottles, where thinner wall sections can pull inward very quickly if negative pressure develops.
IBC pressure & vacuum caution
IBC leak testing may be carried out at relatively low positive pressure, often around 2–3 psi. This is a leak-test condition, not a working-pressure rating for the IBC.
During CPP® development testing across different IBC designs, standard IBC bottles have shown visible bulging or panel movement at relatively low positive pressure, while negative pressure can pull the side walls inward very quickly. Wall thickness and stiffness vary between IBC manufacturers, models, ages and bottle designs.
This vent must not be used to treat an IBC as a pressure vessel. Always follow the IBC manufacturer's permitted operating limits.
How the vent works
During gravity discharge from an IBC, liquid leaving the container must be replaced by air. The vacuum-relief function allows air into the container to reduce the risk of the IBC panels drawing inward.
If pressure builds inside the container, the pressure-relief function allows excess internal pressure to vent through the same assembly.
Use guidance
- Suitable for controlled gravity discharge and intermittent decanting.
- Do not assume the vent can match the full outlet flow of an open IBC valve.
- Watch the IBC walls during discharge. If they begin to pull inward, stop the flow immediately and allow air to enter before continuing.
- For applications requiring sustained high-rate discharge, use a venting arrangement with sufficient verified air-in flow for the required liquid discharge rate.
Next-generation CPP® IBC vent in development
CPP® is currently developing a new high-flow pressure and vacuum relief vent for IBC applications. Testing is being carried out across a range of new and used IBC designs to measure air-in flow, pressure-relief performance and container deformation under realistic operating conditions.
Initial development results indicate a substantial increase in both vacuum-relief and pressure-relief capacity compared with HMVMN20MM027. Production release is targeted for the end of 2026. Final verified performance data and any comparative claims will be published when testing is complete.
Installation
Screw the vent into a compatible 2″ IBC top connection using the correct sealing arrangement. Do not use the vent as justification for pressurising an IBC beyond the container manufacturer's permitted operating limits.
Material and application guidance
Check the CPP® chemical resistance guide and Material Application Statement for suitability with your liquid and operating conditions.
