FAQ02758 of General Purpose Relays FAQ

MYH-series General-purpose Relays are encased in a sealed metal structure containing nitrogen gas. A metal case is used to provide resistance against harmful corrosion to prevent corrosive gases from penetrating the Relays.

Classification by Type of Protection

Item		Features	Representative model	Atmosphere conditions
Mounting structure	Type of protection			Dust and dirt	Corrosive gases
Plug-in Relays	Unsealed (cased)	Structure that protects against contact with foreign material by means of enclosure in a case (designed for manual soldering)	MY	Some protection (No large dust or dirt particles inside Relay.)	No protection
	Plastic sealed	Structure sealed with resin case or cover that provides resistance against atmospheres containing corrosive gases affecting the Relay	G2A-434	OK	OK See note.
	Hermetically sealed	Structure with metal or glass enclosure and base hermetically sealed with inert gas (N2) that provides resistance against harmful corrosion to prevent corrosive gases from penetrating the Relay	MYH	OK	OK
Screw (metal)- mounting Relays	Open	Structure that provides protection against contact and penetration of foreign matter	MM2	No protection	No protection
	Enclosed (cased)	Structure that protects against contact with foreign material by means of enclosure in a case (designed for manual soldering)	G7J	Some protection (No large dust or dirt particles inside Relay.)	No protection

Note:

Using Relays in an Atmosphere Containing Corrosive Gas
(Silicon, Sulfuric, or Organic Gas)

Do not use Relays in a location where silicon gas, sulfuric gas (SO₂ or H₂S), or organic gas is present.

If Relays are stored or used for an extended period of time in an atmosphere of sulfuric gas or organic gas, contact surfaces may become corroded and cause contact instability and obstruction, and terminal soldering characteristics may be degraded.

Also, if Relays are stored or used for an extended period of time in an atmosphere of silicon gas, a silicon film will form on contact surfaces, causing contact failure.

The effects of corrosive gas can be reduced by the processing shown in the following table.