While silo protection systems are vital to safe production, if they aren’t installed correctly, adequately maintained and routinely checked, they risk failure. Not only will a failure cause operational disruption and production loss, but it’s a health concern for both your employees and the environment. One of the earliest signs of silo failure is easily spotted, even from the ground – a silo blowing dust out of the PRV during a fill, as this video from Hycontrol shows:
There are additional warning signs for SPS failure however, and knowing what they are can help you avoid catastrophic consequences – and save you time, money and productivity along the way. Here’s some key problems to watch for:
Blocked, leaking or damaged PRV
Problem: One of the most common misconceptions in the powder-based industry is that pressure relief valves emit product when they are operating correctly. In fact, the opposite is true – this is a red flag for SPS failure. If product is being emitted, it means your PRV is being put under pressure, most often due to failure of the monitoring and control system.
Damaged or faulty pressure sensor
Problem: Pressure sensors are essential for preventing silo over-pressurization – it takes as little as 1 psi to rupture a silo or blow the filter unit off the roof. This is why your SPS should be detecting pressures as low as 40 millibar (0.5 psi). Unfortunately, these sensors are often forgotten and rarely tested. In addition, they are often incorrectly set by applying hand pressure to the sensitive rubber diaphragm, a force 50 times greater than the required set point, leaving it unsuitable for safety application.
Blocked air filter
Problem: When operating correctly, comprehensive silo protection systems indicate when filter cartridges are degrading and/or air is not being vented quickly enough. Poor filtration, where particles of product cause congestion, traps pressure inside the vessel and increases risk. A high number of over-pressurization events would typically indicate blocked filters or poor driver delivery behavior, illustrating why a pressure sensor and a system that records pressure events are both essential.