Typical Feed Water Heater Isolation System Sempell Model AVS 4/5 HP Preheater Protection Valve

Features

• Body of forged steel.

• Body in form piece to reduce a number of welds and fittings.

• Body also available as a single block type - thereby eliminating the nozzle welding seams.

• Fast switch over, in order to avoid damaging further HP feedwater pipes.

• Alternatives with a moderation of the closing speed by means of various solutions. This is then required if it is possible for the water to hit and damage the separation wall of the preheater or if the customer specifies the operating times.

• Simultaneous operation of two main valves with one pilot valve.

• Open the preheater only after equalization of the pressure - increases safety because work is done behind the valve.

• System medium operated - no heavy actuator.

• Alternatives available for selection of the pilot valves.

General application

In the event of a defective tube system these valves are designed to stop the feed of high pressure feedwater and to bypass it around a heater or a group of heaters in shortest time. Protection is achieved in the system by installing a quick closing changeover valve in front of and a quick closing check valve behind the heaters in the pipework. The motive power is the feedwater pressure, so that the system is failsafe if either electric or pneumatic supplies fail.

Sizes: DN 80 - 500

Temperature: 100 - 360°C

Body material: 1.0460 1.7335 1.5415 1.6368 A105 A182F12

Pressure class: PN 160 - PN 500

Quick - closing valves

For easy mounting of the AV valves, they should preferably be installed in vertical position. Their pressure losses are equivalent to 90° bands and are substantially more advantageous as compared with T-fittings. In case of preheater groups, the valve bodies being designed as fittings, may serve for the feed-water line to be distributed to the individual preheaters.