ASCO PB26A P Series Fixed Deadband Midsize Pressure Switch Instruction Manual

1. Introduction

This instruction manual provides essential information for the safe and effective installation, operation, and maintenance of the ASCO PB26A P Series Fixed Deadband Midsize Pressure Switch. The PB26A unit incorporates the unique ASCO TRI-POINT alternating fulcrum balance plate to control the operation of one or more electrical snap-action switches. The electrical snap-action switch, along with its adjusting mechanism, is a fully-tested, self-contained subassembly.

Key features of this pressure switch include a set point repeatability of ±1% of the operating range, accessibility of all wiring terminals, adjustments, and visual scales from the front, a compact size, the ability to mount in any position, and a rugged, vibration-resistant design.

2. Safety Information

• Always disconnect power before installing or servicing the switch.
• Installation and maintenance should only be performed by qualified personnel.
• Ensure the pressure switch is used within its specified operating ranges for pressure and electrical ratings.
• Protect the unit from environmental conditions exceeding its IP54 rating.
• Refer to local electrical codes and regulations for proper wiring practices.

3. Product Overview

The ASCO PB26A is a midsize pressure switch designed for industrial applications. It features an open frame design and a 1/4" pipe size connection. The switch is engineered for reliable performance in various pressure control systems.

Figure 1: ASCO PB26A P Series Fixed Deadband Midsize Pressure Switch. This image shows the pressure switch from an angled view, highlighting its robust metal casing, the electrical terminal block with three screw terminals (two with green-capped wires, one with a gold screw), and the internal mechanism. The product label with "ASCO", "CAT. PB26A", and electrical ratings is visible on the side.

Key Features:

• Set point repeatability: ±1% of operating range.
• Front accessibility for all wiring terminals, adjustments, and visual scales.
• Compact size for versatile installation.
• Mounts in any position.
• Rugged and vibration resistant construction.

4. Setup and Installation

4.1 Mounting

The ASCO PB26A pressure switch is designed to be mounted in any position. Secure the unit firmly using appropriate fasteners through the designated mounting holes on the frame. Ensure the mounting surface is stable and free from excessive vibration.

4.2 Pressure Connection

Connect the pressure source to the 1/4" pipe size inlet. Use appropriate sealing tape or compound to ensure a leak-free connection. Do not overtighten the connection, as this may damage the switch or piping.

4.3 Electrical Wiring

All wiring terminals are accessible from the front of the switch. Refer to the electrical ratings on the product label and the table below for proper wiring. Ensure all connections are secure and comply with local electrical codes.

The switch features SPDT (Single Pole Double Throw) contacts. Connect the power supply and controlled device according to your application's requirements. The terminal block includes connections for Normally Open (NO) and Normally Closed (NC) circuits.

5. Operating Instructions

5.1 Setting the Pressure Switch

The ASCO PB26A pressure switch features an adjustable set point. The adjusting mechanism and visual scales are accessible from the front of the switch. To adjust the set point:

1. Ensure the system is depressurized and power is disconnected before making adjustments.
2. Locate the adjustment screw or mechanism on the front of the switch.
3. Turn the adjustment screw clockwise to increase the set pressure or counter-clockwise to decrease it.
4. Use the visual scale to approximate the desired set point. Fine-tuning may be required after initial setup.
5. Once adjusted, repressurize the system and test the switch operation to verify the set point. The set point repeatability is ±1% of the operating range.

5.2 Understanding Deadband

This pressure switch features a fixed deadband. The deadband is the difference between the pressure at which the switch actuates (set point) and the pressure at which it de-actuates. For the PB26A, the minimum deadband is 0.4 psi. This fixed deadband helps prevent rapid cycling of the controlled device.

6. Maintenance

The ASCO PB26A pressure switch is designed for minimal maintenance. However, periodic checks are recommended to ensure optimal performance and longevity.

• Visual Inspection: Regularly inspect the switch for any signs of physical damage, corrosion, or loose connections.
• Connection Integrity: Check all electrical and pressure connections to ensure they are secure and free from leaks.
• Environmental Protection: Ensure the switch's IP54 rating is maintained. Protect it from excessive dust, moisture, or corrosive environments.
• Functionality Test: Periodically test the switch's operation by varying the system pressure to confirm it actuates and de-actuates at the desired set points.
• Cleaning: If necessary, clean the exterior of the switch with a soft, dry cloth. Do not use harsh chemicals or abrasive materials.

7. Troubleshooting

This section provides guidance for common issues encountered with the ASCO PB26A pressure switch.

• Switch Not Actuating:
  • Verify power supply to the circuit.
  • Check electrical connections for looseness or corrosion.
  • Ensure system pressure reaches the set point.
  • Inspect the pressure line for blockages or leaks.
  • Confirm the set point adjustment is correct.
• Switch Not De-actuating:
  • Ensure system pressure drops below the de-actuation point (set point minus deadband).
  • Check for any mechanical obstruction preventing the switch from resetting.
  • Verify electrical connections.
• Erratic Operation:
  • Check for excessive vibration at the mounting location.
  • Inspect for pressure fluctuations in the system.
  • Ensure stable power supply.
  • Verify the integrity of the pressure connection.

If issues persist after troubleshooting, contact ASCO technical support.

8. Specifications

• Model Number: PB26A
• Brand: Asco
• Series: P Series
• Type: Fixed Deadband Midsize Pressure Switch, Open Frame
• Switch Pressure Operating Range: 2-18 psi
• Proof Pressure: 60 psi
• Minimum Deadband: 0.4 psi
• Pipe Size: 1/4 inch
• Set Point Repeatability: ±1% of operating range
• Connector Type: SPDT (Single Pole Double Throw)
• International Protection Rating: IP54
• Connectivity Protocol: X-10
• Mounting: Mounts in any position
• Construction: Rugged and vibration resistant
• Package Dimensions: 7.09 x 2.95 x 1.18 inches
• Item Weight: 14.46 ounces
• Manufacturer: ASCO Valve Inc.
• Date First Available: October 21, 2019

Electrical Ratings:

Refer to Table 1: Electrical Ratings in the Setup and Installation section for detailed electrical specifications.

9. What's in the Box

• 1 x ASCO PB26A Pressure Switch

10. Warranty and Support

Specific warranty information for the ASCO PB26A pressure switch is typically provided at the point of purchase or through the official ASCO documentation accompanying the product. For detailed warranty terms and conditions, please refer to your purchase receipt or contact ASCO directly.

For technical support, service, or further inquiries, please contact ASCO customer service or visit their official website. Ensure you have your product model number (PB26A) and serial number (if available) ready when contacting support.