Core Summary
The range of a pressure switch is merely a starting point. What truly determines its long-term stability and reliability are medium compatibility, electrical interface, and setting method. Align these three aspects first, and then revisit the range and price. Doing so can save considerable costs associated with subsequent replacements and downtime.
1. The medium determines the material of the sensing element
Whether it's a diaphragm or a piston, the choice is not random
When the medium being measured is clean and has low corrosivity, the diaphragm switch responds sensitively with good repeatability, making it suitable for low pressure and differential pressure scenarios. When the medium is viscous, contains particles, or has high pressure, the piston structure is more resistant to impact and has a longer lifespan. Bailey & Mackey's Type 1381 series adopts a diaphragm structure, while Type 1581 follows the piston route, each corresponding to different working conditions.
The materials of wet components need to be reviewed
Stainless steel wetted parts are a common requirement in industrial sites, but whether it's 304 or 316 depends on whether the medium is weakly corrosive. Choosing the wrong material can lead to corrosion pits on the wetted surface after a few months, and the switching action point may drift, often necessitating a complete replacement.
II. Do not modify the electrical interface on-site
Normally open and normally closed states, as well as wiring configurations, are determined in advance
Many buyers only consider whether the switch output is SPDT or DPDT, yet overlook whether the wiring terminal is a DIN plug, cable outlet, or terminal strip. Once the interface of the on-site PLC cabinet is finalized, making temporary wiring changes is both labor-intensive and prone to leaving hidden dangers. Bailey & Mackey offers a variety of switches with different electrical connection options. Before ordering, send a photo of the control cabinet interface to the supplier for verification, which is much cheaper than reworking afterwards.
The load type determines the contact capacity
When directly using solenoid valves or motor starters and only providing input signals to PLCs, the requirements for contact capacity vary significantly. If the load current exceeds the rated value of the contact, its lifespan will plummet. It is essential to include the load type in the purchase list so that the supplier can match the appropriate switch model.
III. The Setting Method Affects Operation and Maintenance Efficiency
Fixed differential pressure or adjustable differential pressure
Some applications only require a fixed action point, while others necessitate adjusting the reset differential pressure based on season or process. Bailey & Mackey's visual setting series allows for observation of the setting position without removing the cover on-site, making it particularly suitable for pump stations and air compressor stations that require frequent inspections.
Is there any adjustment tool on site
Certain precision models require specialized tools for adjustment. If the on-site tools are incomplete, each adjustment will incur additional outsourcing services. When selecting a model, it is important to inquire whether specialized tools are required to avoid small subsequent modifications turning into significant expenses.
IV. Consider the measurement range as the last consideration
Leave sufficient overvoltage margin
Measuring range coverage of normal operating pressure is only the baseline. Water hammer, pump start-stop, and rapid valve closure can all cause transient overpressure. It is generally recommended that the operating pressure fall within the 30%–70% range of the measuring range, and it is necessary to confirm that the switches can withstand the expected transient overpressure [please verify].
Accuracy is not necessarily the higher the better
For general pump control and air compressor control, a switch with an accuracy of ±1%–±2% is sufficient; higher accuracy is only required for metering or safety interlocking. Each increase in accuracy level will result in changes to both price and lead time, so there is no need to pay for performance that is not utilized.
V. Procurement Checklist
Confirm the medium type, temperature, and corrosivity
Select the diaphragm or piston structure
Check the material of wet components
Clarify electrical interfaces, contact types, and load types
Confirm whether the setting method is convenient for on-site maintenance
The measurement range is selected based on 30%–70% of the normal pressure, leaving an overpressure margin
Parameter Table (Selection Comparison)
> The above is a selection guideline. Specific parameters are subject to the original datasheet provided by Bailey & Mackey. QN TECHNOLOGY offers selection verification for models such as Type 1381, Type 1581, and Type 3311. We welcome you to send us your operating parameters for comparison.
Need technical documentation or a quotation for this model or solution?
Tell us the brand and model — our engineers will provide selection advice, technical documentation and a quotation.