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FAQ: Valvario Proof of Closure and Visual Indication

Q: Why do I have to specify a flow direction when ordering valVario solenoid valves with proof of closure and visual indication?

A: Perhaps the best way to answer this question is to start with a quick description. Many manufacturers differentiate between models featuring proof of closure (POC) and those with visual indication (VI), but Kromschröder does not. If a VAS solenoid valve is ordered and either proof of closure or visual indication is specified, the valve will arrive with both features.

The solenoid actuator on non-POC models may be swiveled a full 360 degrees, to accommodate wiring as well as to allow equipment operators and maintenance professionals to easily see the blue lamp, which indicates when the valve is receiving power. Models with proof of closure and visual indication do not have this freedom of movement, and must be selected with the flow direction in mind, so that the electrical box is easy to access, the blue indicating lamp is easy to note at a glance, and the visual indication is visible. This is why your Kromschröder representative asks you which viewing side is needed, or the direction of flow, while processing your order.

How do you know which models to select? Kromschröder’s Type Code is there to relay the crucial information for a given model quickly. Here is an example of a common VAS solenoid valve for gas with proof of closure and visual indication:


Each part of the Type Code gives you a distinct piece of information.

VAS = ValVario Solenoid Valve for Gas and Air
1 = Size 1
T = T-Product (with approvals for use in the North American Market, with ¼” NPT screw plugs in valve body)
25 = 1” (approx. 25mm) internal thread connection
N = NPT thread
/N = Quick opening and closing
Q = Main voltage 120VAC, 50/60Hz
SL = With 120VAC proof of closure switch and visual indication, viewing side left in the direction of flow

Knowing that the “SL” on the back of your VAS means “viewing side left in the direction of flow” is helpful, but most people need a little more of an explanation. We try to phrase it this way:

If the flow is moving Right to Left, then the valve should be “viewing side left.”

If the flow is moving Left to Right, then the valve should be “viewing side right.”

If still unsure, think of the technician, who will install and wire the valve. As he is performing these actions, which best describes the direction of flow? Will it be coming from his left-hand side, and moving toward his right, or the other way around?

There are dozens of manufacturers providing the industry with components for combustion systems, and everybody does things differently. Please don’t hesitate to email questions that arise as a result of, or due to confusion regarding, a pending Kromschröder purchase to

Posted by  b-olstrad ; Published August 23, 2012

 Categories: FAQs, Industrial Solenoid Valves, Kromschroder

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