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In addition to the fluid type, actuators also vary in the manner in which the energy is stored to operate the valve on demand as follows:

The performance standard of ESDVs may include the specification and testing of a closure time (e.g. to close in less than 10 seconds) and the specification and measurement of an acceptable leakage rate of fluid through the closed valve.[2]

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However, sudden closing of a valve in a piping system may lead to water hammer or implosion so in special cases there may be additional items connected to the shutoff valve, such as a pressure relief valve or an aerator valve.

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Water Heater

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A blowdown valve (BDV) is a type of shutdown valve designed to depressurize a pressure vessel by directing vapour to a flare, vent or blowdown stack in an emergency. BDVs fail-safe to the open position upon failure of the control system.[1] The type of valve, type of actuation and performance measurement are similar to an ESD valve.

For air intake shut down, two distinct types are commonly utilized, i.e. butterfly valves and swing gate or guillotine valves. Because diesel engines ignite fuel using compression instead of an electronic ignition, shutting off the fuel source to a diesel engine will not necessarily stop the engine from running. When an external hydrocarbon, such as methane gas, is present in the atmosphere, it can be sucked into a diesel engine causing overspeed or over revving, potentially leading to a catastrophic failure and explosion. When actuated, ESD valves stop the flow of air and prevent these failures.

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For shutdown valves used in safety instrumented systems it is essential to know that the valve is capable of providing the required level of safety performance and that the valve will operate on demand. The required level of performance is dictated by the Safety Requirements Specification, where eventually a Safety Integrity Level (SIL) is indicated. In order to maintain the level of performance required during the valve lifetime, the Safety Maintenance Manual prescription shall be fulfilled: one of the possible requests is to test the valve. Among the others 2 types of testing methods are:

For fluids, metal seated ball valves are used as shut-down valves (SDV's). Use of metal seated ball valves leads to overall lower costs when taking into account lost production and inventory, and valve repair costs resulting from the use of soft seated ball valves which have a lower initial cost.

In a solenoid-operated safety shutoff valve, a spring action closes the valve instantly when an electric current fails and the solenoid ceases to be energized. The solenoid circuit is generally arranged so that it is broken upon failure of any element of the system. This valve cannot be re-opened until the solenoid is again energized. The coil of the valve solenoid must be connected in series with all of the elements. For this to operate, fuel, air and steam pressure can be converted to electrical signals by means of bellows, a bourdon tube, or a diaphragm-operated mercury switch.

A shutdown valve (also referred to as SDV or emergency shutdown valve, ESV, ESD, or ESDV; or safety shutoff valve) is an actuated valve designed to stop the flow of a hazardous fluid upon the detection of a dangerous event. This provides protection against possible harm to people, equipment or the environment. Shutdown valves form part of a safety instrumented system. The process of providing automated safety protection upon the detection of a hazardous event is called functional safety.

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As a homeowner, you want to make sure that every investment into your home not only benefits you, but also improves the home. Tankless water heaters are an investment every homeowner should consider. At Noritz, we strive to provide the very best. We make retrofitting easy with the size and flexibility of our heaters. Installation requirements are minimal, meaning your new tankless heater can be installed in the same space as your old tank based water heater, and it takes up less space. Let’s take a look a few of our options and how they stand out.

Shutdown valves are primarily associated with the petroleum industry although other industries may also require this type of protection system. ESD valves are required by law on any equipment placed on an offshore drilling rig to prevent catastrophic events like the BP Horizon explosion in the Gulf of Mexico in 2010.

As shutdown valves form part of a SIS it is necessary to operate the valve by means of an actuator. These actuators are normally fail safe fluid power type. Typical examples of these are:

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A safety shutoff valve should be fail-safe, that is close upon failure of any element of the input control system (such as temperature controllers, steam pressure controllers), air pressure, fuel pressure, current from a flame detector, or current from other safety devices such as low water cutoff, and high pressure cutoff.

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Straight-through flow valves, such as rotary-shaft ball valves, are typically high-recovery valves. High recovery valves are valves that lose little energy due to little flow turbulence. Flow paths are straight through. Rotary control valves, butterfly valve and ball valves are good examples.

The Noritz NRCR offers the latest cutting edge recirculation technology in a tankless water heater. This unit is also equipped with high quality stainless steel heat exchangers for extreme corrosion and thermal stress resistance, giving your tankless a longer lifespan. In addition, a recirculation pump comes integrated with the unit to give you hot water faster and without the wait.

The type of actuation required depends upon the application, site facilities and also the physical space available although the majority of actuators used for shutdown valves are of the spring return type due to the fail safe nature of spring return systems.

Our EZ series offers you top of the line tankless water heaters that we think are a must for any homeowner. The EZ series are condensing tanks that come in a variety of sizes and are designed to save space in your home. Better yet, they bring you a reliable, endless supply of hot water. Take a look at the available options in the EZ series, and the benefits they offer you.