MANUAL OF NON-RETURN VALVES (NRV)

1. Introduction

Scope

This manual provides guidelines for the installation, operation, maintenance, inspection, warranty coverage, and service procedures for Non-Return Valves (NRV).

Applications

Non-Return Valves are automatic valves designed to allow fluid flow in one direction while preventing reverse flow. They are commonly used in:

• Water Distribution Systems
• Pumping Stations
• Water Treatment Plants
• Sewage Treatment Plants
• Irrigation Systems
• Industrial Pipelines
• Fire Fighting Networks
• HVAC Systems
• Power Plants

NRVs protect pumps, pipelines, and equipment from damage caused by backflow and pressure reversals.

2. Installation Guidelines

Pre-Installation Inspection

Before installation:

• Verify valve size, pressure rating, and material compatibility.
• Inspect valve for transportation or handling damage.
• Check internal moving components for free movement.
• Confirm flow direction marked on the valve body.

Pipeline Preparation

• Thoroughly clean and flush the pipeline.
• Remove rust, welding slag, stones, and foreign materials.
• Ensure proper pipe alignment.
• Avoid excessive stress on the valve body.

Installation Position

Horizontal Installation

• Preferred installation method.
• Ensure valve cover is positioned upward.

Vertical Installation

• Allowed only for upward flow direction.
• Confirm compatibility with valve design.

Flange Installation

• Use suitable gasket material.
• Tighten bolts evenly in cross sequence.
• Avoid excessive bolt torque.

Installation Precautions

• Ensure sufficient straight pipe lengths where possible.
• Do not install against the indicated flow direction.
• Provide proper pipeline supports.

3. Operation Instructions

Automatic Operation

Non-Return Valves operate automatically:

• Forward flow opens the valve.
• Reverse flow closes the valve automatically.
• No manual operation is required.

Operating Precautions

• Never force valve movement manually.
• Operate within rated pressure and temperature limits.
• Avoid severe pressure surges.
• Ensure correct installation orientation.

Startup Procedure

1. Verify installation direction.
2. Gradually introduce system pressure.
3. Observe valve operation.
4. Check for leakage and unusual noise.
5. Verify proper closure during flow stoppage.

4. Maintenance Schedule

Monthly Inspection

• Inspect for external leakage.
• Check flange joints.
• Listen for abnormal vibration or chatter.
• Verify system performance.

Quarterly Inspection

• Inspect body coating condition.
• Check moving components.
• Examine seat condition where accessible.
• Verify proper backflow prevention.

Annual Inspection

• Remove valve for internal inspection if required.
• Inspect disc and seat surfaces.
• Examine hinge pin and bushings.
• Replace worn seals and gaskets.
• Perform operational testing.

Recommended Spare Parts

• Disc Assembly
• Seat Rings
• Hinge Pins
• Springs (where applicable)
• O-Rings
• Gaskets
• Fasteners

5. Warranty Coverage

Warranty Exclusions

Warranty does not cover:

• Improper installation.
• Reverse installation.
• Operation beyond rated limits.
• Water hammer damage.
• Corrosion from unsuitable media.
• Unauthorized modifications.
• Normal wear and tear.

6. Expected Service Life

Factors Affecting Service Life

• Flow Velocity
• Water Quality
• Pressure Variations
• Water Hammer Frequency
• Operating Conditions
• Maintenance Practices
• Environmental Exposure

Proper maintenance can significantly extend valve service life.

7. Customer Responsibilities

The customer shall:

• Ensure correct installation practices.
• Maintain maintenance and inspection records.
• Operate within rated conditions.
• Conduct regular inspections.
• Protect the valve from external damage.
• Promptly report operational abnormalities.
• Follow manufacturer recommendations.

Failure to comply may affect warranty eligibility.

8. Warranty Claim Procedure

Step 1 – Claim Submission

Provide:

• Purchase Order Number
• Invoice Copy
• Valve Identification Details
• Installation Date
• Description of Defect
• Photographs of the Issue

Step 2 – Technical Review

The submitted information will be reviewed to determine:

• Installation compliance
• Operating conditions
• Maintenance history
• Warranty applicability

Step 3 – Inspection

Where necessary:

• Site inspection may be conducted.
• Valve may be requested for detailed examination.

Step 4 – Resolution

Based on technical findings:

• Repair
• Component Replacement
• Valve Replacement
• Technical Recommendation

will be provided in accordance with warranty terms.

Safety Precautions

• Depressurize the system before maintenance.
• Never dismantle the valve under pressure.
• Wear appropriate personal protective equipment (PPE).
• Use approved lifting methods for large valves.
• Follow all plant safety procedures.

Document Retention

Maintain installation records, maintenance logs, inspection reports, and warranty documentation throughout the valve's service life for warranty and operational reference.