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Use case: Bleed valves in Ammonia or Fertilizer plants



An ammonia or fertilizer plant has various use cases for manual valve positioning that can be made economical viable through IoT. Ammonia is produced on large scale mainly for production of fertilizer and is considered highly dangerous for multiple reasons.


In atypical ammonia or fertilizer plant, you find thousands of manual valves that are often only operated during maintenance or turnarounds. Due to the large number of manual valves, it can be challenging to keep a good oversight of their position during the different stages of production or maintenance.

Producing ammonia requires intense heat and high pressure. On top, ammonia is very dangerous since it is highly flammable and toxic. Leaving a valve accidentally in the wrong position has proven to be dangerous and has let to incidents and catastrophic accidents in the past all across the industry.

 In today’s industry, manual valve position checks are still used to verify the correct valve position. Different companies use different means to identify the critical valves in the field and label or lock (LOTO – Lock Out Tag Out) themas part of these procedures. However, this still leaves significant room for mistakes. Different reports still report human error to be the main cause in70-80% of the incidents.



A specific set of valves in the ammonia industry are the bleed valves. These valves are only opened during maintenance to prevent that pressure is built up or to release trapped fluids or gasses. These valves are highly critical when production is started since they allow an open connection towards the atmosphere. When accidentally left open while production starts, ammonia is leaked into the atmosphere.

To further improve safety and increase visibility around valve operations during maintenance, Aloxy’s valve positioning solution is introduced. An LPWAN network(DASH7 or LoRaWAN) is installed and the bleed valves in the plant have been equipped with the Aloxy Pulse valve position sensors.

The AloxyPulse sensor can be installed during production using a universal bracket without any modifications to the valve. The actual valve position of each bleed valve is now in real-time available in the control room or on the operator’s handheld.



Bleed valves are often small valves (¼” or ½”) and can easily be overseen during a visual inspection. On ammonia refrigeration systems the bleed valves can also easily get plugged, only appearing to be closed. However, when the system comes back online, the plug is pushed out and the line is open creating a leak.

 By applying the Aloxy Pulse sensors on the valve handwheel or lever, all bleed valve positions can be visualized and monitored through a control room dashboard in real time.

The team involved in performing the maintenance activity will use the dashboard as an additional safety layer to confirm all monitored manual valves are in their right position during the different stages. They can check the real-time position of every valve and immediately identify when the required position and current position do not align. Alternatively, the dashboard can trigger an alert when it observes that a valve is not positioned correctly according to the current stage of maintenance or operations.

Before proceeding with signing off on a procedure or work permit, an additional check is done from the control room to verify all bleed valves are closed.



It is always difficult to put an exact number on safety, however a famous expression says: “if you feel safety is expensive, why don’t you try an accident”.

Spills of ammonia have a large risk of to cause harmful effects on workers and the public. If the ammonia is under pressure, risk of exposure even increases since larger quantities of the refrigerant have the potential for rapid release into the atmosphere. Also, explosions have been attributed to releases of ammonia contaminated with lubricating oil.

An accident has multiple negative aspects associated, first and foremost, the injury or loss of people. Secondly the economic costs are tremendous. The cost of plant downtime is often estimated around €500K a day and damaged assets add up quickly. Finally, accidents get a lot of media coverage which damages the company’s reputation.

When you monitor bleed valves in real time and have better oversight of your manual valves, there is less risk in performing these maintenance activities and overall safety levels for workers and the surrounding areas increase significantly.