Rockwell Automation 836T Series Differential Pressure Controller

Rockwell Automation 836T Series Differential Pressure Controller

Product Core Description

1. Basic specifications and applicable scenarios

Model classification: Bulletin 836T, including three types: Type 1, 4, and 13, all designed to be oil tight.

Protection ability: It can resist oil/water flow erosion, prevent cotton wool and dust from entering the shell, and is suitable for scenarios that require environmental sealing.

Connection specifications: The pressure interface is 1/4 "-18 N.P.T.F (American dry sealed cone pipe thread), and the electrical interface includes 1/2" -14 N.P.T (optional Pg 13.5 BS20 specification).

Bellows material: provides two options, each suitable for different media——

Copper alloy corrugated pipe: suitable for water, air, and non corrosive liquids/gases;

316 stainless steel corrugated pipe: suitable for liquids/gases with stronger corrosiveness.

2. Core Structure and Function

Core components: including Top Bellows, Bottom Bellows (mechanical linkage), Contact Block, Adjustment Differential Screw "B", Pressure Adjustment Difference Bushing "A", Operation Indicator, optional Pilot Light, etc.

Pressure sensing principle: The action is triggered by the pressure difference between two corrugated tubes, regardless of the actual gauge pressure of the system; Adjustable "trip pressure" and "reset pressure", with the difference between the two being the "differential control pressure".

Contact module configuration: provides two specifications to meet different circuit requirements——

Contact module type Contact configuration Circuit function

2-circuit: 1 set of normally open (NO)+1 set of normally closed (NC) supports single pole double throw (SPDT) or independent circuit operation with the same polarity

4-circuit with 2 sets of normally open (NO) and 2 sets of normally closed (NC) supports double pole double throw (DPDT) or two sets of electrically isolated single pole double throw circuits, including isolated terminal 9, which can be connected to external power supply

Working principle

The controller responds to pressure difference changes through a "trigger reset" cycle, with the following specific logic:

1. Trigger (Trip) action (contact switching)

When any of the following conditions are met, the contact module switches states:

The pressure of the bottom corrugated pipe is higher than the preset trigger pressure difference of the top corrugated pipe;

The pressure of the bottom corrugated tube is constant, and the pressure of the top corrugated tube decreases by the preset trigger pressure difference.

2-channel circuit: normally closed circuit (1-2) is open, normally open circuit (3-4) is closed;

4-channel circuit: Two sets of normally closed circuits (1-2, 5-6) are disconnected, and two sets of normally open circuits (3-4, 7-8) are closed.

2. Reset action (contact recovery)

When any of the following conditions are met, the contact returns to its initial state:

The pressure of the bottom corrugated pipe is lower than that of the top corrugated pipe;

The pressure of the bottom corrugated pipe remains constant, while the pressure of the top corrugated pipe increases.

2-channel circuit: normally closed circuit (1-2) is closed, normally open circuit (3-4) is open;

4-channel circuit: Two sets of normally closed circuits (1-2, 5-6) are closed, and two sets of normally open circuits (3-4, 7-8) are disconnected.

3. Key definitions

Trip Pressure: The minimum pressure difference required to trigger contact switching;

Reset Pressure: The maximum pressure difference that triggers contact recovery;

Differential control: The difference between the trigger pressure and the reset pressure can be independently adjusted.

Installation requirements

1. Mechanical installation

Fixing method: It needs to be fixed on a stable base with two screws, and the installation hole specification is "2-17/64" diameter (6.75mm)+2-23/32 "countersunk hole (69mm)", which can be operated without disassembling the front cover;

Prohibited operation: Do not support the controller solely through electrical or pressure interfaces; When tightening the electrical and pressure interfaces, a support wrench should be used to avoid damaging the components.

2. Precautions for Pre Installation

Before installation, it is necessary to complete the parameter settings ("Setting Control" steps) according to the instructions, otherwise the system cannot be connected;

The pressure interface distinguishes between the "Lower Pressure Bellows Connection" and the "Higher Pressure Bellows Connection", which need to be connected to the corresponding system.

Parameter setting steps

The factory default setting is "maximum trigger pressure difference+minimum control pressure difference" (adjusting the sleeve "A" about 1 inch from the bottom of the housing), which requires the assistance of a pressure gauge for calibration. It is divided into two steps:

1. Trigger the Difference Pressure Setting

The top corrugated pipe is vented to the atmosphere (without pressure), and a constant pressure is applied to the bottom corrugated pipe to trigger the target pressure difference;

Insert a 1/8 "diameter rod into the hole of the adjusting sleeve" A ", rotate the sleeve to the left until the controller" triggers "(circuit 1-2 is disconnected, circuit 1-2 and 5-6 are disconnected);

At this point, the pressure of the bottom corrugated tube is the set trigger pressure difference.

2. Differential Adjustment Control

Adjustment logic: Adjusting screw "B" only changes the reset pressure difference (does not affect the triggering pressure difference) - turn screw "B" clockwise → increase the control pressure difference (reset pressure difference decreases); Turn counterclockwise → reduce the control pressure difference (reset pressure difference increases); When screw "B" is tightened against the bottom of the front cover, control the pressure difference to be minimized.

Specific steps:

Rotate screw "B" clockwise for about 12 turns;

Apply pressure according to the "trigger pressure difference setting" steps to trigger the controller, then reduce the pressure to the target control pressure difference and maintain it;

Rotate screw "B" counterclockwise until the controller is "reset" (2 circuits 1-2 are closed, 4 circuits 1-2, 5-6 are closed);

Repeat the "trigger reset" cycle several times to ensure stable settings;

Screw "B" should not protrude from the bottom of the housing, and adjusting sleeve "A" should not exceed the control range marked on the dial.

3. Complete the setup

After parameter calibration, connect the top corrugated pipe (low pressure end) to the system, install the front cover and tighten 4 screws (torque 6-8 inch pounds) to ensure sealing. It is recommended to regularly check the system pressure and recalibrate as needed.

Optional accessories and maintenance

1. Pilot Light Options

Specification: High brightness neon lamp, suitable for 120V, 60Hz scenes, can be pre installed in the factory or installed on site;

Ordering method: Add "N9" (such as 836T-XXX-N9) after the existing controller model, special specifications require customization;

Wiring rules:

2-channel circuit: Connect the light wire to the load terminal, connect 1-2 for "on when pressure rises" and 3-4 for "on when pressure drops";

4-channel circuit: Connect the light wire to the load terminal (1-2/5-6 or 3-4/7-8), or connect it to an external power source through isolation terminal 9 (ensuring the same polarity of the circuit);

Safety reminder: Disconnect the power supply before installation/maintenance to prevent electric shock.

2. Component replacement and maintenance

Contact module replacement: 2-channel module replacement kit model 836T-N1, 4-channel module kit model 836T-N2;

Overall maintenance: As the controller is an integrated structure, it is recommended to return all faults except for the contact module to the factory for repair (the factory will calibrate to the best performance and test according to specifications);

Nameplate protection: The standard controller nameplate comes with a removable protective film, which needs to be removed during final installation.

Safety and Compliance

CE certification: The product complies with CE standards;

Operation warning: Adjust the components within the marked range to avoid mechanical damage; Corrosive media should use 316 stainless steel corrugated pipes to prevent material failure;

WEEE and Environmental Protection: The document does not mention specific environmental compliance information, please refer to Rockwell Automation's General Environmental Policy.