Pressure switches are an indispensable component found in all type of industries. Tough a simple instrument the function it serves is not only key to a healthy production but also for the safety of plant and machineries.

Today there are many technologies used in making a pressure switch which provides various options to the user. This makes it important that we select the correct instrument for our application.

Below are some key points to consider when selecting a pressure switch.
Online Pressure Switch Selector Link  (← Click Here)


The housing used to make the switch ensures that proper material is used so that a correct switch is used in an environment conducive to good service life. Various material options are available like die cast Aluminum, Stainless Steel in various grades like SS304, SS316 etc. and Polyester or other Plastic based compounds.  

  • While Aluminum option with optional various pain coatings like epoxy is a good option for most applications.  
  • The SS variant are required in environment with chemical fumes or corrosive gases like in a fertilizer or chemical plants.  
  • The Plastic enclosure are used in basic indoor applications and are attractive due to its low pricing. 

Enclosures are classified as Weather Proof based on IP rating or as Flame Proof for different Gas Groups like I, IIA, IIB or IIC. 

1.  Weather Proof Enclosures: 

The IP Code (or International Protection Rating, sometimes also interpreted as Ingress Protection Rating) consists of the letters IP followed by two digits and an optional letter. As defined in international standard IEC 60529, it classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water in electrical enclosures.  

The first digit ranges from 0 to 6 and indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects. The second digit ranges from 0 to 9 and indicates the level of protection of the equipment inside the enclosure against harmful ingress of water. 

Below are some IP rating commonly found in pressure switches available in the market 


IP:33 : 

First Digit 3 indicates enclosure protected against object of size > 2.5  mm.  

Second Digit 3 indicates enclosure protected against water falling as a spray at any angle up to 60° from the vertical.


  IP:66IP:66 :

First Digit 6 indicates the enclosure is dust-tight and there is no ingress of dust; complete protection against contact.  

Second Digit 6 indicates the enclosure is protected against water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction. 

RTIP:67 :  

First Digit 6 indicates the enclosure is dust-tight and there is no ingress of dust; complete protection against contact.  

Second Digit 7 indicates ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1 m of submersion).  

2. Flameproof Enclosures: 

These switches use heavy protective enclosure usually made of die cast steel or Aluminium. If heat or sparks from faulty equipment within the enclosure ignite flammable gas present with it the resulting explosion is contained within the enclosure.   

Note: (i) Suitable flameproof cable glands must be used to ensure proper protection and (ii) Opening the enclosure while powered is strictly not allowed. 

Environment which have explosive gases are classified as below Gas Grades 

  • Group I – Methane  
  • Group II is subdivided into three types, viz. IIA, IIB, IIC  

IIA represents Propane or gases and vapours of equivalent hazard 

IIB represents Ethylene or gases and vapours of equivalent hazard 

IIC represents Hydrogen, Acetylene or gases and vapours of equivalent hazard 

DiaphragmSensor : 

The sensing mechanism used in the making of a pressure switch is an important criteria that has to be considered while selecting a pressure switch. Various options are available in the market today below are some commonly available variants. 

Bellow Type Pressure SwitchBellow : 

A convoluted bellow in a capsule is used to sense the pressure. Variants made in Phosphor Bronze and SS316L are available in market. Advantage the bellow type mechanism offers is better repeatability upto 0.5% FSR and also this mechanism offers switch to have adjustable dead band. The limitations are relatively low pressure range and the material used for manufacturing the bellows are limited hence these cannot be used for highly aggressive or demanding media. 

Diaphragm : 

The process pressureis applied to a diaphragm to generate a force which is compared to that of a pre-compressed range spring. These generally provide repeatability upto 1% FSR but the major advantage it offers is that avide variety of materials are used in manufacturing the diaphragm ranging from standard Rubber (NBR) and SS316L to exotic materials like Monel, Hastelloy etc which makes these switches suitable for aggressive and corrosive media. These can be used for high pressure ranges upto 700 Bar. 

PSD-4Electronic : 

These switches use either a ceramic or a stainless steel diaphragm to sense pressure. These are multifunctional as it is like a combination of a pressure transmitter, gauge and switch. These offer 1 or 2 selectable switching outputs (PNP/NPN) with optional I-O Link connectivity. These are robust and compact space-saving devices with user friendly key pad for setting of set points, differential and other functionality like changing display units (bar, psi etc).  

3. Dead Band : 

Dead band is the difference between the set and reset point of a pressure switch. For example we need to turn a pump off when the pressure reached 10 bar and the pumps has to re-start if the pressure falls below 8 bar. So the dead band required is 2 Bar (10-8).  Pressure switches are available with below types of dead bands. 

Fixed Dead Band: Usually diaphragm type pressure switches come with this option where the dead band is non-adjustable generally 6 to 10% of the Full Scale. 

Narrow Band Adjustable: Bellow type pressure switches can provide this option where the dead band is adjustable within 6% of the Full Scale 

 Wide Band Adjustable: This option is also found with bellow type pressure switches where the dead band is adjustable 15% to 60% of the Full Scale. 

 Fully Adjustable: Electronic pressure switches being a solid state device offers this unique feature of differential adjustable upto 100% of the Full Scale. 

 Range : This refers to the upper and lower limit within which the switch can be used. However for best accuracy the set point should fall between 35% to 70% of the range span for electro-mechanical switches. Also on and off settings should not exceed the upper or lower range value. For example a switch with range span 1 to 10 Bar is best suited to be set between 3.5 to 7 Bar for best performance. For solid state electronic switches generally set point should be above 25% of the range. 

The maximum pressure upto which the switch is not damaged is mentioned as “maxium working pressure (MWP)”.   

Note: MWP is not the range and should not be used to select the instrument. Generally MWP is higher for diaphragm type pressure switches compared to bellow type. 

Micro-Switch : This is the heart of a pressure switch. A micro-switch makes or breaks an electronic circuit when a pressure switch operates. Various options like SPDT (1 NO+1NC), DPDT (2 NO+2NC) etc are available. Select suitable switch ratings after confirming contact load. If the contact load is excessive for the contacts, the contacts may weld or shift, possibly resulting in short-circuits or burning when power is supplied. 

Pressure Switch Selector on BUY PNEUMATICS 

Buy Pneumatics   is the leader in online sales for Pressure Switches (SWITZER/INDFOS) has created a Pressure Switch Selector. This is a drop-down based selector model – which helps users identify a suitable switch for their application.  

Go to Pressure Switch Selector page by clicking here

Switzer, Indifos product selection