Glacier Diesel Power | 5-20 PSI Adjustable Hobbs Switch

Glacier Diesel Power Universal Adjustable Hobbs Pressure Switch | 5–20 PSI (HOBBS-5-20)

Description

Control a pressure-activated electrical circuit with the Glacier Diesel Power Universal Adjustable Hobbs Pressure Switch.

This universal pressure switch features an adjustable activation range from 5 to 20 PSI, allowing the switching point to be matched to the requirements of the system being monitored or controlled. It can be incorporated into custom fuel, oil, air, boost, or other compatible pressure-based electrical systems where a circuit needs to respond when pressure reaches a predetermined level.

Unlike a pressure sender, which produces a variable signal for a gauge or electronic controller, a Hobbs-style pressure switch functions as an electrical on/off device. Once system pressure reaches the adjusted switching point, the internal contacts change state and can be used to activate a relay, warning light, auxiliary pump, control module, or another low-current circuit.

Because this is a universal electrical component, the installer is responsible for confirming pressure compatibility, port size, contact configuration, electrical load, wiring logic, and safe installation for the intended application.

Features

• Universal adjustable pressure switch
• Adjustable operating range from 5 to 20 PSI
• Pressure-activated electrical switching
• Suitable for custom control and warning circuits
• Can be used with a properly selected relay
• Allows the activation point to be adjusted for the application
• Useful for fuel, oil, air, boost, and other compatible pressure systems
• Compact mechanical switching design
• No external electronic controller required
• Product SKU: HOBBS-5-20

What Is a Hobbs Pressure Switch?

A Hobbs-style switch is a pressure-operated electrical switch.

Inside the switch, system pressure acts against a diaphragm or piston mechanism. When pressure reaches the adjusted threshold, the mechanism changes the position of the internal electrical contacts.

Depending on the switch configuration and the way the circuit is wired, that change can be used to:

• Turn a circuit on
• Turn a circuit off
• Activate a warning indicator
• Trigger a relay
• Enable an auxiliary component
• Signal that minimum pressure has been reached
• Signal that pressure has fallen outside the desired range

The switch does not display the actual pressure and does not send a continuously changing pressure signal. It simply changes electrical state when the selected pressure threshold is crossed.

Adjustable 5–20 PSI Operating Range

The pressure setting can be adjusted within a range of approximately 5 to 20 PSI.

This allows the installer to select a switching point appropriate for the system rather than being limited to one fixed setting.

Possible examples include:

• Activating a warning light if a fuel system does not build the expected pressure
• Enabling an auxiliary circuit after oil pressure develops
• Activating a relay when boost pressure reaches a selected level
• Controlling a secondary pump based on system pressure
• Confirming that an air-pressure circuit has reached its minimum operating threshold

The correct pressure setting depends entirely on the application. Do not choose the activation point based on a generic recommendation without first understanding the normal operating range and minimum safe pressure for the system.

Pressure Switch vs. Pressure Sender

A pressure switch and a pressure sender perform different jobs.

Pressure Switch

A pressure switch provides an on/off electrical response when pressure reaches a set point.

It is commonly used for:

• Warning lights
• Relays
• Safety shutdowns
• Auxiliary pump control
• Pressure-confirmation circuits

Pressure Sender

A pressure sender produces a variable electrical signal that changes with pressure.

It is commonly used with:

• Analog gauges
• Digital displays
• Data loggers
• Engine-control modules
• Programmable controllers

This Hobbs switch should not be purchased when the application requires a variable pressure reading.

Common Uses

The adjustable Hobbs switch may be incorporated into properly designed systems such as:

• Diesel lift-pump control circuits
• Fuel-pressure warning systems
• Engine-oil-pressure safety circuits
• Auxiliary oil-pump controls
• Turbocharger boost-activated circuits
• Water-methanol control systems
• Air-compressor systems
• Pneumatic control systems
• Industrial pressure-confirmation circuits
• Custom automotive relay controls

These are general examples only. Compatibility must be confirmed for the specific fluid, pressure source, electrical system, and installation environment.

Fuel System Application

In a diesel fuel system, a pressure switch may be used to monitor whether the lift pump has developed a predetermined minimum pressure.

For example, the switch could be wired through a relay or warning-light circuit to indicate when pressure is above or below the chosen threshold.

However, an on/off pressure switch provides less diagnostic information than a pressure gauge. It may indicate that the selected threshold has been crossed, but it does not show:

• Actual fuel pressure
• Pressure fluctuations
• Pressure loss under acceleration
• Gradual filter restriction
• Pressure at idle compared with load
• How far the system is above or below the switch point

For complete fuel-system diagnosis, a gauge or pressure sensor remains the better tool.

Oil-Pressure Safety Application

A pressure switch can be used in custom oil-pressure safety circuits to control a relay after the engine develops oil pressure.

This type of arrangement may be used to:

• Enable an electric fuel pump after startup
• Activate an auxiliary lubrication system
• Trigger a warning light
• Interrupt a circuit when oil pressure is lost

A pressure switch should not be treated as a substitute for the factory oil-pressure monitoring system unless the entire circuit has been properly engineered and tested.

Improper wiring could prevent a critical component from operating or could allow the engine to continue running after pressure is lost.

Boost-Activated Application

Because the adjustable range extends up to 20 PSI, the switch may also be used in certain boost-activated control circuits.

Potential uses include triggering:

• A relay
• A warning indicator
• An auxiliary pump
• A water-methanol system
• A secondary control stage
• A data-acquisition input

The switch does not regulate boost pressure. It only responds electrically when the pressure at its port reaches the adjusted threshold.

Do not connect the switch directly to a high-current component unless its published electrical rating specifically permits it.

Glacier Tech Tip

Use the Hobbs switch to control a relay rather than routing the full current of a high-draw component through the switch.

A relay allows the pressure switch to control a small trigger current while the relay contacts carry the larger electrical load required by the pump, solenoid, fan, or other accessory.

This arrangement can help reduce:

• Electrical load through the pressure switch
• Contact arcing
• Voltage drop
• Heat at the switch terminals
• Premature contact failure

The relay, fuse, wiring, and connectors must all be sized correctly for the accessory being controlled.

Why a Fuse Is Still Required

A pressure switch controls when current flows, but it does not provide circuit protection.

The controlled circuit should include a properly sized fuse or circuit breaker located near the electrical power source.

A correctly designed circuit generally includes:

• Fused battery or ignition power
• Properly sized wiring
• Relay where required
• Secure ground
• Protected terminals
• Weather-resistant connections
• Strain relief
• Routing away from heat and abrasion

Never rely on the Hobbs switch itself to protect the wiring from a short circuit.

Normally Open vs. Normally Closed Operation

Pressure switches may use different internal contact arrangements.

Normally Open

A normally open circuit does not pass current in its resting state. The contacts close when the switch reaches its pressure threshold.

This arrangement may be used to activate an accessory or indicator after pressure develops.

Normally Closed

A normally closed circuit passes current in its resting state. The contacts open when the pressure threshold is reached.

This arrangement may be used for certain warning, interruption, or safety circuits.

The exact contact arrangement and terminal function must be verified before installation. Do not assume the switch’s wiring logic based only on terminal appearance.

Use a multimeter to confirm continuity with no pressure and again while applying controlled pressure.

Understanding Switch Hysteresis

Mechanical pressure switches normally have some difference between the pressure at which they activate and the pressure at which they reset. This difference is often called hysteresis or deadband.

For example, a switch adjusted to activate near a selected pressure may not reset at exactly the same pressure as the system falls.

This helps prevent rapid electrical cycling when pressure fluctuates around the activation point.

Because the exact differential is not listed on the current product page, applications requiring an extremely precise activation and reset point should be tested before final installation.

How to Set the Activation Pressure

Do not attempt to set the switch accurately using only the position of the adjustment screw.

The correct procedure is to use a controlled pressure source and an accurate reference gauge.

A typical adjustment process includes:

1. Connect the switch to a regulated pressure source.
2. Install an accurate reference pressure gauge.
3. Connect a multimeter across the appropriate switch terminals.
4. Apply pressure gradually.
5. Observe the pressure where the contacts change state.
6. Adjust the switch in small increments.
7. Repeat the test until the desired activation point is reached.
8. Slowly reduce pressure and observe the reset point.
9. Repeat the test several times to confirm consistency.

Avoid applying pressure beyond the switch’s published limits.

Why Bench Testing Matters

A universal pressure switch should be tested before it is relied upon to control an important circuit.

Bench testing confirms:

• Contact configuration
• Terminal function
• Activation pressure
• Reset pressure
• Adjustment direction
• Switching consistency
• Correct multimeter behavior
• Proper wiring logic

Testing also reduces the chance of discovering a wiring or adjustment problem after the switch has been installed in a difficult-to-access location.

Installation Location

Install the switch where it can accurately monitor the pressure required by the control system.

Depending on the application, this may be:

• At a fuel-filter housing
• In a fuel-pressure test port
• In an oil gallery
• On a remote manifold
• In a boost-reference line
• At an air-pressure manifold
• In a tee fitting near the monitored component

Avoid installing the switch where it will be exposed to:

• Excessive engine vibration
• Direct exhaust heat
• Impact damage
• Unprotected road debris
• Water intrusion at the terminals
• Hose strain
• Rigid plumbing that places leverage on the switch body

A remote-mounted pressure manifold or flexible hose may be preferable in high-vibration applications.

Thread and Port Compatibility

Before installation, verify the thread type and size of both the switch and the intended pressure port.

Do not force together fittings that appear similar. Common pipe and straight-thread fittings may have different:

• Thread angles
• Thread pitches
• Sealing methods
• Tapers
• Diameters
• Seat designs

A mismatched fitting can damage the switch or create a pressure leak.

The current Glacier product listing identifies the pressure range but does not publish the thread specification. Confirm the port dimensions before selecting adapters or installation fittings.

Sealing the Pressure Connection

Use a sealant compatible with the fluid, temperature, fitting material, and thread design.

For tapered pipe threads:

• Apply sealant only to the male threads.
• Keep sealant away from the first thread when possible.
• Prevent excess sealant from entering the pressure passage.
• Do not overtighten the switch.

Excessive thread sealant can contaminate the system or block the small pressure opening.

Do not use thread sealant on straight-thread fittings that seal with an O-ring, crush washer, flare, or machined seat unless the fitting manufacturer specifically requires it.

Fluid Compatibility

Do not assume that every pressure switch is compatible with every liquid or gas.

Before installation, confirm compatibility with:

• Diesel fuel
• Gasoline
• Engine oil
• Transmission fluid
• Coolant
• Compressed air
• Water-methanol mixtures
• Refrigerants
• Hydraulic fluid
• Chemical or industrial fluids

Material incompatibility can cause swelling, corrosion, leakage, diaphragm deterioration, or switch failure.

The current product listing identifies the switch as universal but does not publish detailed wetted-material specifications. Applications involving unusual fluids or safety-critical systems should be verified before installation.

Electrical Installation Notes

Before wiring:

• Disconnect battery power.
• Determine whether the circuit requires normally open or normally closed operation.
• Verify the switch terminals with a multimeter.
• Identify the current draw of the controlled component.
• Install a relay when the load exceeds a low-current trigger circuit.
• Install a properly sized fuse.
• Use automotive-grade wire and terminals.
• Protect exposed connections from moisture and corrosion.
• Route wiring away from exhaust heat and moving components.
• Secure wiring to prevent vibration damage.

Do not allow the switch body or pressure fitting to become the unintended ground path unless the circuit has been specifically designed that way.

Wiring Through a Relay

A common pressure-controlled relay arrangement uses the Hobbs switch only as the relay trigger.

The circuit can be organized so that:

1. Fused power feeds the relay’s high-current terminal.
2. The relay sends power to the accessory when energized.
3. The Hobbs switch controls the relay coil circuit.
4. The switch changes state at the selected pressure.
5. The relay activates or deactivates the accessory.

The exact terminal numbers and ground strategy depend on the relay and desired operating logic.

Always verify operation before connecting the final accessory.

Important Safety Considerations

Do not use this pressure switch as the sole protection device for a system where switch failure could cause personal injury, fire, engine damage, or equipment damage.

Critical systems may require:

• Redundant pressure monitoring
• A mechanical relief valve
• An independent warning system
• A programmable safety controller
• Manual override provisions
• Fail-safe wiring
• Periodic functional testing

A pressure switch is one component within a control system. Overall safety depends on how the entire circuit is designed.

Common Problems

Circuit Activates at the Wrong Pressure

Bench-test the switch with a regulated pressure source and accurate gauge. Do not estimate adjustment based on screw position.

Switch Changes State but the Accessory Does Not Run

Check the fuse, relay, power supply, ground, accessory wiring, and voltage at the load.

Accessory Cycles Rapidly

Pressure may be fluctuating near the switch point. The application may require a different setting, additional pressure stabilization, or a controller with programmable delay.

Pressure Leaks Around the Switch

Verify thread compatibility, sealing method, adapter condition, and installation torque.

Switch Works During Testing but Not on the Vehicle

Check wiring polarity where applicable, grounding strategy, pressure at the actual mounting location, vibration, heat exposure, and terminal corrosion.

Activation Pressure Changes

Verify that the adjustment has not moved and that the switch is not exposed to excessive pressure, vibration, temperature, or incompatible fluid.

Applications

This is a universal adjustable pressure switch and is not limited to one vehicle, engine, or fuel system.

Potential applications include:

• Dodge Ram Cummins fuel systems
• Ford Power Stroke fuel or oil circuits
• GM Duramax auxiliary systems
• Custom diesel builds
• Gasoline performance vehicles
• Industrial engines
• Agricultural equipment
• Construction equipment
• Air-compressor systems
• Custom automotive electrical circuits

Universal does not mean automatically compatible. The installer must verify all mechanical and electrical requirements.

Is This the Correct Component?

This switch may be appropriate when:

• You need an on/off pressure-based electrical signal.
• The desired activation point is between 5 and 20 PSI.
• You are building a custom warning or control circuit.
• You can verify the switch’s contact configuration.
• You can use a relay for higher-current loads.
• The switch materials are compatible with the monitored fluid.
• The port can be connected using the correct fitting or adapter.

This is not the correct component when:

• You need a variable-output pressure sender.
• You need to display actual pressure on a gauge.
• The desired switching point is outside 5–20 PSI.
• The application requires a published, extremely precise switching differential.
• The fluid compatibility has not been confirmed.
• The switch would be the only protection for a safety-critical system.
• The circuit’s current exceeds the switch’s electrical rating.

Important Notes

• Adjustable from 5 to 20 PSI
• Universal application
• Functions as an on/off pressure switch
• Does not display actual pressure
• Does not replace a pressure sender
• Verify contact configuration before wiring
• Verify thread size and port compatibility
• Verify fluid compatibility
• Use a relay for higher-current accessories
• Protect the circuit with a correctly sized fuse
• Bench-test and adjust before final installation
• SKU: HOBBS-5-20
• This item is currently listed as a preorder product on the Glacier Diesel Power website.

Common Failure Point: Using the Switch to Carry Too Much Current

One of the most common mistakes in a pressure-switch installation is wiring a high-current accessory directly through the switch.

Electric pumps, solenoids, compressors, fans, and heaters may draw considerably more current than a small mechanical pressure switch is intended to carry. Excessive electrical load can cause:

• Contact arcing
• Internal heat
• Voltage drop
• Intermittent operation
• Welded contacts
• Premature switch failure

Use the Hobbs switch as a control input and allow a correctly rated relay to carry the accessory’s main electrical load.

Complete Your Pressure-Control System

Pair the adjustable Hobbs switch with the appropriate Glacier Diesel Power installation and diagnostic components:

• Fuel-pressure sender tees
• Pressure-test fittings
• Remote pressure manifolds
• Thread adapters
• Fuel and oil hose assemblies
• Automotive relays
• Fuse holders
• Electrical connectors
• Pressure gauges
• Warning indicators
• Boost-reference fittings

The Glacier Diesel Power 5–20 PSI Adjustable Hobbs Switch provides a flexible pressure-activated control point for custom automotive, diesel, and industrial systems. Its adjustable range allows the installer to select the desired activation pressure, while proper relay control, circuit protection, bench testing, and compatibility verification help create a dependable installation.