Southern African specialised oil and gas equipment supplier Energas Technologies has introduced safety product manufacturer Protectoseal’s Series 10 2″ tank blanketing valve (TBV) to the South African market.

Introduced in July, the company explains that the valve enables an effective method of preventing fires in flammable liquid storage tanks, as tank blanketing controls the formation of explosive vapours or air mixtures. Blanketing minimises evaporation of the stored product and, in so doing, reduces emission levels and product loss. It also protects the tank’s contents from external contamination.

Energas product engineer Laetitia Botha says that tank blanketing has always been a staple in the company’s range of safety products. “It works on the basic principle of creating a blanket of inert gas in the tank’s vapour space to prevent atmospheric air from entering the tank, and so maintaining a nonflammable atmosphere.”

She adds that Energas has stocked Protectoseal products for about ten years and that the introduction of Series 10 TBV is a great way for the company to offer a solution for larger flow applications.

How it Works
Botha explains that a blanketing valve regulates the pressure of the inert gas layer on top of the stored liquid in a tank. The valve senses the pressure of the tank blanket and opens to allow in more inert gas when the pressure drops below the set pressure. In response to the pressure, and in building back up to the set pressure, the valve closes and stops the flow.

The Protectoseal Series 10 TBV comprises two separate valves working in tandem. “The pilot valve is controlled by the sensed tank pressure and, in turn, controls the opening and closing of the main valve, which provides flow into the tank from the inert gas supply,” explains Botha.

She adds that, “the main components of the pilot valve are a pressure sending chamber and a poppet, which can move up and down. The main valve, on the other hand, has a piston which can move to control flow into the tank.”

When the flow of gas into the tank increases the tank pressure above the set pressure, the sense diaphragm is pushed up, allowing both the stop and the poppet to rise – this is made possible by the spring force under the poppet – until the poppet reseals. Botha says that once this has happened, the dome pressure is allowed to build back up to the inlet pressure, pushing the piston closed once more, which ultimately shuts off flow to the tank.

Features and Benefits

The Series 10 TBV is specifically designed for tank blanketing and its pilot-operated design offers a tight operating brand. It boasts the most compact design and the fewest external connections of any other pilot-operated valve on the market. It is also field serviceable.

“The valve is available in a range of materials. The metal parts are available in 316 stainless steel and the seals and gaskets are available in Buna-N, Neo prene, Viton, ethylene propylene diene monomer rubber, Chemraz or Kalrez.”

Botha points out that the inlet and outlet connections of the Protectoseal Series 10 are available in many threaded and flanged combinations. In the case of applications involving high purity products, Protectoseal Pure-Tech high purity blanket valves are available.

Special Options
Botha notes that the Series 10 offers two special options, namely status port and single port sensing options. “The status port option is primarily used in remote areas and gives an indication of the open versus closed status of the valve. It offers remote monitoring using a pressure transmitter, and sounds an alarm when blanketing gas flow is excessive. It enables a reduction in operating costs by allowing monitoring of blanking gas usage.

“The single port sensing option boasts single connection mounting, eliminates the need for a separate sense-like connection to the tank and efficiently controls tank pressure,” she explains.

Protectoseal is a leading manufacturer of environment-sensitive safety products and an important supplier to Energas Technologies’ range of products, Botha remarks.

“By offering its latest in TBV technology, we are able to offer our customers not only a safety-enhancing product, but one that facilitates operational efficiency and minimises wastage. We’re delighted to bring [this product] to South Africa and look forward to facilitating and supporting its successful uptake in this market,” she concludes.