SAFETY ALERTS RISK GALLERY WHAT IS SILO PROTECTION? SHIELD LITE SPS SILO SERVICING CONTACT

SILO PROTECTION SAFETY ALERTS


SAFETY BRIEFING 1: Pressure relief valve near-miss event

Ready-mix, concrete and block works have silos on-site that are pneumatically filled from road tankers. Many of the sites have silos fitted with pressure relief valves as their only protection from over-pressure.

The photographs show how they can be rendered completely ineffective by constant use and poor maintenance. Pressure relief valves are continuously relieving pressure without the reason being investigated or the cause eliminated. The road tankers are capable of blowing product into the silos at pressures as high as 2 bar.

The silo, however, is not a certified pressure vessel and is at risk of rupture at any pressure above 1psi. An effective silo protection system provides automatic closure of the delivery valve. Lack of this has resulted in silos being ruptured and filter systems being ejected from the silo roof.

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Blocked pressure relief valves are a sign of silo pressure problems

SAFETY BRIEFING 2: Neglecting maintenance of silo protection equipment can be dangerous

Silos on ready-mix, concrete and block plants are filled from road tankers using pressurised air. It has been identified that there is a danger of silo ruptures or filters blowing off. This problem can even happen with the correct MPA-recommended safety equipment installed.

Not only does this pose an immediate risk, but the threat from working at height adds to the problem.


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Solid powder in and around a pressure valve will block it

SAFETY BRIEFING 3: Blocked filters can go undetected without a structured maintenance programme in place

During tanker delivery procedures at a UK concrete block plant, drivers were recording multiple high-pressure events and safety shutdowns. The silo protection equipment was passing pre-delivery tests, and the air venting filter unit had recently been serviced. Hycontrol engineers were asked to investigate why the pressure alarm was triggering with such regularity.

Their investigation highlighted a problem with one of the solenoids controlling airflow to the reverse jet cleaning nozzles, resulting in serious blockages on three of the seven filter cartridges.

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A blocked air vent filter cartridge
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HYCONTROL LTD Larchwood House, Orchard St, Redditch B98 7DP UK. Tel: +44 (0)1527 406800 Email: sales@hycontrol.com