Pressure Switch for Pump Control: How DR3602 Cut Nuisance Trips by 75%

Why Were Nuisance Trips Costing Us $12,000 Every Month?

In an industrial chemical processing line, our pumps were repeatedly stopping even though the system appeared to be operating within its normal pressure range. The problem became increasingly expensive. Each hour of unplanned downtime cost approximately $1,500 in lost production. With the process line experiencing multiple nuisance trips during a shift, the monthly impact quickly reached approximately $12,000. The first warning sign was a gradual increase in pressure across a process filter. The filter was becoming more restrictive, but the maintenance schedule was based primarily on operating time rather than actual pressure conditions. As a result, the filter could be either replaced too early or allowed to operate too long. When pressure crossed the existing switch threshold, the pump stopped. Operators then had to reset the relay, restart the pump, and determine whether the trip represented a genuine process problem. Eventually, the repeated alarms created another problem: alarm fatigue. When operators see too many false alarms, they can become less responsive to genuine process abnormalities. We needed a more flexible way to monitor pressure and control the pumps.

Why Pump Control Cannot Rely on a Single Pressure Setpoint

A conventional pressure switch is often configured around one switching point.

For simple applications, this may be sufficient.

Pump control systems, however, frequently require more than one condition.

For example:

• Start a backup pump when pressure becomes too low.
• Stop or alarm when pressure becomes too high.
• Detect abnormal pressure conditions.
• Prevent unnecessary switching caused by small fluctuations.

A single switching point cannot independently manage all of these conditions.

This becomes particularly important in filtration and pumping applications.

As a filter becomes progressively clogged, the pressure relationship across the system changes. A pump may need to respond to a low-pressure condition while a separate high-pressure condition may indicate excessive restriction or another process fault.

A Pressure Switch for Pump Control therefore needs to do more than simply detect whether pressure has crossed one threshold.

It needs to provide flexible control logic for the actual operating conditions.

The Problem With Fixed Setpoints

Another issue we encountered was switching instability near the pressure threshold.

Pressure in an industrial process rarely remains perfectly constant.

Small variations can occur because of:

• Pump startup
• Valve movement
• Flow changes
• Filter loading
• Temperature changes
• Pressure pulsation
• Changes in process demand

If a pressure switch changes state immediately every time the pressure crosses a single threshold, the relay can repeatedly switch on and off.

This behavior is commonly known as chattering.

For pump control, repeated switching is undesirable.

It can increase:

• Pump starts and stops
• Mechanical wear
• Electrical switching cycles
• Operator interventions
• Unnecessary alarms

A properly configured hysteresis creates a separation between the switching and reset conditions.

This allows the system to tolerate normal pressure fluctuations while still responding to meaningful pressure changes.

The DR3602 supports independently configured relay switching and release values, allowing hysteresis to be set for each control point.

How a Pressure Switch for Pump Control Improved Our Process

We replaced the existing single-relay arrangement with the DR3602 Intelligent Pressure Switch. The key advantage was its two independent relay outputs. Instead of asking one switch to perform a single task, we could configure two separate pressure conditions. For our application, one relay was configured to respond to a high-pressure condition, while the second relay was used for a low-pressure control condition. This provided a much more practical control strategy for the process line. The DR3602 is designed to integrate pressure measurement, local display, relay control, and optional analog output into one instrument. Its product specifications list two relay outputs and optional 4–20 mA output, with 24 VDC power supply.

Independent High and Low Pressure Control

The two-relay configuration is particularly useful when a process requires both high- and low-pressure responses.

For example:

High-pressure condition

If pressure rises above the defined upper limit, Relay 1 can activate an alarm or control function.

Low-pressure condition

If pressure falls below the defined lower limit, Relay 2 can activate another control function, such as starting a standby pump.

The exact relay logic depends on the application and control architecture.

The important point is that the two conditions can be configured independently rather than relying on a single pressure threshold.

This provides engineers with greater flexibility when designing pump protection and process control systems.

Hysteresis Helps Prevent Unnecessary Pump Switching

The DR3602 also allows the switching and release values for each relay to be configured separately. For example, instead of having a pump switch state at exactly one pressure and immediately reverse when pressure moves slightly in the opposite direction, engineers can define a suitable operating band. This hysteresis helps prevent unnecessary switching caused by small pressure fluctuations. The DR3602 manual explicitly defines hysteresis as the difference between the relay’s switching and release values, with separate settings available for Relay 1 and Relay 2. For industrial pump control, this can be particularly useful where pressure naturally fluctuates around the desired operating point.

Local Display Makes On-Site Adjustment Easier

The DR3602 uses a 4-digit LED display for real-time pressure indication and on-site parameter adjustment. This is important for maintenance engineers. Instead of connecting a laptop or relying entirely on the PLC interface, technicians can view the pressure directly at the instrument and adjust the relevant control parameters locally. The product page specifically lists a 4-digit LED display and on-site setting of up to two control points.

For commissioning and maintenance work, this can simplify:

• Setpoint verification
• Relay testing
• Pressure troubleshooting
• Parameter adjustment
• Routine inspection

Integrating the Pressure Switch With a PLC

Pump control does not always operate as a standalone function. Many industrial facilities already have PLC or SCADA systems that need access to pressure information. The DR3602 supports an optional 4–20 mA output, allowing the measured pressure to be transmitted to compatible control or monitoring systems. RS485 is also available as an optional output according to the product information. This creates a useful architecture:

Pressure Measurement → DR3602 → Relay Control + PLC Signal 

The relay outputs can handle local control functions, while the analog or digital signal can provide pressure information to the larger automation system. This reduces the need for separate pressure measurement and switching devices in applications where both functions are required.

What Changed After Installation?

Within the first week after installing the DR3602, the number of nuisance trips decreased by approximately 75% in our application. The improvement came from several changes working together. First, the two independent relay outputs allowed the process to respond differently to high- and low-pressure conditions. Second, the adjustable switching and release values reduced unnecessary relay cycling caused by normal pressure fluctuations. Third, the local digital display made it easier for technicians to verify actual pressure conditions during maintenance. As a result, operators spent less time manually resetting relays and restarting pumps. Instead, they could focus on the underlying process. The estimated savings from reduced downtime, emergency maintenance, and pump wear allowed the investment to pay back in less than two months.

Why Pressure-Based Pump Control Is Better Than Calendar-Based Maintenance

One of the most important lessons from this application was that equipment condition does not always follow the calendar. A filter does not become clogged because a certain number of days have passed. It becomes clogged because contaminants accumulate and restrict flow. Similarly, a pump does not necessarily require intervention because it has operated for a predetermined number of hours. Actual operating conditions provide better information. Pressure can act as an important indicator of process condition. By monitoring pressure continuously and setting appropriate alarm or control thresholds, maintenance teams can respond to actual process behavior rather than relying entirely on fixed schedules. This approach can support a more condition-based maintenance strategy.

Pressure Switch vs. Pressure Transmitter for Pump Control

A Pressure Switch for Pump Control can be useful in many industrial applications where pressure needs to trigger different control actions.

Typical examples include:

Water Pump Systems

Control pumps according to pressure conditions and provide high- or low-pressure alarms.

Filtration Systems

Detect increasing pressure caused by filter loading and trigger maintenance or process responses.

Hydraulic Systems

Protect pumps and hydraulic equipment from abnormal pressure conditions.

Chemical Processing

Monitor process pressure and provide independent alarm or control outputs.

Industrial Automation

Provide pressure-based switching signals to PLCs and other control systems.

Process Water Systems

Control pumps and monitor pressure in water circulation and distribution systems.

The DR3602 product page lists applications including petroleum, chemical, electric power, mechanical engineering, process control, hydrology, flow measurement, and hydraulic pressure applications.

Pressure Switch vs. Pressure Transmitter for Pump Control

These devices perform different roles.

If your application primarily requires continuous analog measurement, a pressure transmitter may be the better choice.

If the system needs pressure measurement plus direct switching or alarm control, an intelligent pressure switch can simplify the architecture.

Key DR3602 Features

The DR3602 combines several functions that would otherwise require separate components.

Dual Relay Outputs

Two independent relay outputs support high/low alarm functions and pump control applications.

Programmable Switching Points

Each relay can be configured for the required pressure condition.

Adjustable Hysteresis

Independent switching and release values allow engineers to define an appropriate deadband and reduce unnecessary switching.

4-Digit LED Display

Provides clear local pressure indication and on-site parameter adjustment.

Optional 4–20 mA Output

Allows pressure measurement to be integrated with compatible PLC and control systems.

Optional RS485

Provides an additional digital communication option for system integration.

24 VDC Power

Suitable for common industrial control power architectures.

Wide Pressure Range

Available configurations cover approximately -1 bar to 1000 bar, depending on the selected range.

Frequently Asked Questions

What is a Pressure Switch for Pump Control?

A Pressure Switch for Pump Control is a device that monitors system pressure and changes an electrical output when configured pressure conditions are reached. It can be used to start or stop pumps, trigger alarms, or protect equipment.

Can one pressure switch control two pump conditions?

Yes, a pressure switch with two independent relay outputs can be configured for separate high- and low-pressure conditions. The DR3602 provides two relay outputs for this purpose.

What is hysteresis in a pressure switch?

Hysteresis is the difference between the pressure at which a relay switches and the pressure at which it returns to its previous state. It helps prevent rapid switching when pressure fluctuates near a setpoint. The DR3602 allows this difference to be configured through separate switching and release values.

Can the DR3602 connect to a PLC?

Yes. The DR3602 supports an optional 4–20 mA output, and RS485 is also available as an option for system integration.

What pressure ranges are available?

The DR3602 supports configurations from approximately -1 bar to 1000 bar, depending on the selected pressure range and pressure type.

Is the DR3602 suitable for hydraulic systems?

Yes. Fandesensor lists hydraulic pressure among the intended applications of the DR3602.

Conclusion: Smarter Pressure Control Starts With Better Switching Logic

A pump control problem is not always caused by a faulty pump. Sometimes the real problem is the way pressure information is being converted into a control action. A single pressure threshold may be insufficient when a process needs independent high- and low-pressure protection, pump control, and tolerance for normal pressure fluctuations. A Pressure Switch for Pump Control with multiple relay outputs and configurable hysteresis provides a more flexible approach. In our application, the DR3602 reduced nuisance trips by approximately 75%, reduced manual operator intervention, and helped the process respond more consistently to actual pressure conditions. For industrial applications that require pressure measurement, alarm control, and pump switching in one device, the DR3602 Intelligent Pressure Switch is worth evaluating.

Hysteresis and deadband are important concepts in industrial measurement and control because they help define how an instrument responds when a process variable changes direction. The International Society of Automation (ISA) provides technical guidance and terminology for measurement and control systems. ISA Measurement and Control Standards

Tags: #pressureswitchwithdelaytimer #adjustablehysteresis #NEMA4Xpressureswitch #DR3602