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Pressure Switches, Gold versus Silver contacts

 

 

Gems Sensors offers their mechanical pressure switches with two different types of internal electrical contacts:  silver and gold.  We are often asked:   

When would I specify the standard silver contacts and when would I specify the gold contacts? 

The electrical contacts inside the Gems’ Pressure Switches operate very similarly to the light switch in your home.  When you need light, you flip up the switch, allowing electricity to pass thru the light switch and powering the light.  In the pressure switch, as your fluid enters the pressure switch, the pressure rises, closing a set of electrical contacts, and allowing electricity to pass through the pressure switch to start the process that the pressure switch is monitoring.   

 

The pressure switch can allow electricity to power a light (indicating that there is a problem with your system) or send signal to a PLC ({Programmable Logic Controller} to control a pump up/pump down action) or even set off a buzzer (when there is too little pressure in the system).  The light, PLC and buzzers are all called “loads”.  Each load will draw a certain amount of current through it.   

The standard configuration of the mechanical pressure switches utilizes silver contacts.  Silver contacts are very common, low in cost and perform very well for most applications.  But when you have very low current (for example driving a PLC or an LED), the very low current flow thru the silver contacts actually do not allow themselves to “self-clean” and they will corrode over a period of time and may not actuate correctly.   

 

How does Gems overcome the corrosion issue with silver contacts? 

As a configurable option, Gems offers mechanical pressure switches with Gold contacts.  Gold contacts, by their natural purity characteristics, will resist corroding, providing a perfect contact area for electricity to flow through and provide your system with a much longer life expectancy. 

 

Any tradeoffs? 

Yes, the gold contact option is limited as to how much electricity can pass through them.  As a rule of thumb, if your application draws less than 12 mA (at 12 VDC), then we recommend using the optional Gold contacts.  If you put too much current through the Gold contacts, you will burn the Gold off and defeating the benefit of having the Gold contacts. 

 

Summary:   

If the load in your application does not draw a lot of current, we suggest using the Gold contact option when specifying your pressure switches.  The Gold contacts will stay cleaner for a longer period of time providing you a reliable application. 

 

 

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