Pressure Reducing Valve - VRP Self-Operated for Regulating Two Downstream Pressure Levels

This scope aims to set out the minimum requirements for self-operated pressure reducing valves (RPV) that provide two downstream pressure levels, using a hydraulic pilot device with the function of forcibly reducing the pressure of the water supply network.

Technical Features

The self-operated pressure reducing valve (RPV) for two downstream pressure levels is an instrument designed to reduce the pressure in the distribution network under two downstream pressure levels and allow programmed valve operation at specified times. The technical requirements are as follows:

2.1 Main Valve and Actuator

Construction Type: Full/nominal hydrodynamic passage ball;

Operation Type: "Self-operated" via a pressure-reducing hydraulic pilot device, which can support two downstream pressure levels. Note: Floating pilot devices shall not be used; the pilot device must be replaceable during maintenance.

Hydraulic Circuit: If necessary, the hydraulic circuit can be adjusted to install and operate automatic modulators and data loggers at key points;

Valve Chamber: Optional dual or single diaphragm actuator, replaceable when maintenance is required;

Maximum Working Pressure: 160 to 250 mca (16 to 25 kgf/cm²) (PN 16 or PN 25);

Body: Ductile iron (NBR 6916 ASTM A536), stainless steel, or materials with excellent performance;

Housing: Malleable iron (NBR 6916 ASTM A536) or stainless steel;

Actuator: Ductile iron (NBR 6916 ASTM A536) or stainless steel;

Circular Valve Seat: Stainless steel;

High-Closure Valve Seat: At least 16 mm to eliminate cavitation damage;

Studs: Stainless steel (AISI 304) or materials with excellent performance;

Nuts: Stainless steel (AISI 304) or materials with excellent performance;

Gaskets: Stainless steel (AISI 304) or materials with excellent performance;

Cover Seal: Natural rubber, EPDM, or materials with excellent performance;

Diaphragm: Natural rubber reinforced with nylon or EPDM rubber reinforced with nylon mesh, replaceable during maintenance;

Upper and Lower Diaphragm Support Plates: Made of stainless steel (AISI 304);

Spring: Stainless steel (AISI 302);

Valve Seat: Bronze alloy or stainless steel (AISI 304);

Maximum Working Temperature: 60ºC;

Shaft/Stem: Stainless steel (AISI 304) or materials with excellent performance;

Bearing Bushing: Bronze (ASTM B62 – C83600, ASTM B584), stainless steel, or materials with excellent performance;

Gate Valve: Stainless steel (AISI 410), with removable seals and made of natural rubber, EPDM, or materials with excellent performance;

Gate Valve Seal: Natural rubber, EPDM, or materials with excellent performance;

Sealing Ring: Stainless steel (AISI 304) or materials with excellent performance, removable without the use of glue (Note: Thickness ≥ 16 mm to eliminate cavitation damage);

Flanges: Dimensions comply with ABNT 7675 standard for PN16; flange spacing complies with the provisions for valves below 6 inches in EN 558-1 standard;

V-Port Device: Enables smooth operation at low flow rates;

Coating (Internal and External): High-melting epoxy coating compliant with ASTM-D 1654 or ISO 9227 standard, or fusion-bonded epoxy (FBE) coating. Deposited via electrostatic spraying process in the standard color code specified by the manufacturer, with a final coating thickness of at least 150-250 microns. It must meet hygiene and safety requirements, adhering to Appendix XX of Regulation No. 5 of the Brazilian Ministry of Health. The product used shall be non-toxic and harmless, shall not promote microbial growth, and shall not cause turbidity, discoloration, off-odor, or abnormal taste in the treated water. Epoxy coatings shall comply with ABNT NBR 8219 or Item 4 requirements of NSF61 standard;

Noise: Below 60 dB when operating in critical mode;

Pressure Reduction Ratio (Upstream to Downstream): Minimum (3:1) to maximum (5:1);

Minimum Internal Flow Velocity: 0.5 m/s;

Maximum Flow Coefficient (KVmax): A coefficient representing the maximum flow rate (m³/h), which means the pressure loss is 1 bar (10 mca) when the fluid passes through a fully open valve. Refer to Table 1 based on the DN value;

Table 1 - Maximum Flow Coefficient for Each Nominal Diameter

 

2.2 Control System

The electronic controller is battery-powered (AA alkaline batteries, no external power supply required), allowing programmed valve operation at set times and supporting two downstream pressure levels;

Equipped with a built-in solenoid valve (latching/pulse type), programmable via a mobile app, with Bluetooth communication and a metal controller base;

Protection Class: IP 68;

Pipelines: Copper alloy, stainless steel, or high-performance materials;

Fittings: Copper alloy, stainless steel, or materials with excellent performance;

Accessories (Filters, Pressure-Reducing Pilot Valves, etc.): High-quality alloys or materials compatible with copper;

Needle Stem: Stainless steel (AISI 304) or materials with excellent performance;

Ball Stem: Stainless steel (AISI 304) or materials with excellent performance;

Body: Bronze;

Spring: Stainless steel (AISI 302);

Seals: Natural rubber or materials with excellent performance.

2.2.1 Pilot Valves

Two pressure-reducing pilot valves, thus providing two different downstream pressure setpoints;

Body: Bronze alloy, stainless steel, or materials with excellent performance;

Housing: Bronze alloy, stainless steel, or materials with excellent performance;

Internal Components: Stainless steel;

Diaphragm Cover: Stainless steel (AISI 304);

Adjustment of Hydraulic Circuit: The hydraulic circuit can be adjusted to install and operate automatic modulators and data loggers at key points or conduct corrective observations;

Maintenance: All valve components must be accessible and repairable without removing the valve from the pipeline.

2.3 Pressure Gauges

Installation Position: Must be installed at the pressure outlet, one upstream of the control system and one downstream of the control system;

Sensor Element: Spiral Bourdon tube made of brass alloy or materials with excellent performance;

Housing: Waterproof, made of polished stainless steel sheet;

Bezel: Chromed stainless steel;

Display Panel: Vertical, aluminum, with white base and black engraving;

Diameter: 63 mm;

Measurement Units: mca (meters of water column) and kgf/cm²;

Internal Damping Fluid: Glycerin;

Pointer: Aluminum;

Display Glass: 2 mm flat glass;

Connection: Standard thread diameter ¼" NPT;

Measurement Range: From 0 mca to 25 kgf/cm² (250 mca);

Main Scale: Every 2 units or every 1 unit;

Accuracy: 2% of the full scale;

Safety Valve: Located at the top of the housing (diametrically opposite to the connection).

2.3.1 Measurement Range

Upstream Pressure Gauge: 0 kgf/cm² (0 mca) to 16 kgf/cm² (160 mca);

Downstream Pressure Gauge: 0 kgf/cm² (0 mca) to 16 kgf/cm² (160 mca).

2.4 Maintenance Kit

Each valve must be equipped with a spare parts maintenance kit, which includes: diaphragm, rubber seat seal, and O-ring.

2.5 Impact on Water

In accordance with Appendix XX of the Consolidated Document No. 5 of the Ministry of Health, when installed in a treated water system, the VRP shall not transfer any elements to the water that alter its drinking water conditions and make it unfit for human consumption under any circumstances.

2.6 Harmlessness Report

Material safety report (water impact report), in accordance with Decree GM/MS No. 888 issued by the Ministry of Health on May 4, 2021. This decree specifies procedures for controlling and monitoring drinking water quality and its drinking water standards, and complies with the NSF/ANSI 61 - Drinking Water System Components - Health Effects standard.

Equipment Identification

The valve must be equipped with an identification plate made of non-corrosive material (AISI 304), which must contain at least the following information:

Manufacturer's mark;

Model;

Production serial number;

Pressure class;

Nominal diameter (mm);

Date of manufacture;

Flange drilling standard.

The following castings must also be embossed on the valve body: manufacturer's brand, nominal diameter (mm), and pressure class.

Table 1 - Internal Coding for Two-Stage Pressure Reducing Valves

 

4 Coating (Certificate Issuance)

From the perspective of hygiene and safety, the coating must meet the requirements for use with treated water. The product shall be non-toxic, shall not support microbial growth, and shall not cause turbidity, discoloration, off-odor, or turbidity in the treated water. Meanwhile, it shall comply with the drinking water safety standards specified in Appendix XX of the Unified Standard No. 5 of the Ministry of Health. The coating must be an epoxy resin material compliant with ABNT NBR 8219 or NSF61 standard.

5 Materials (Certificate Issuance)

The supplier must submit chemical analysis and mechanical test certificates for the materials used in the manufacture of the cabinet, cover, disk, stem, plug, spring, and bushing. The certificates must allow traceability of the materials used by subcontractors and must include the specified properties of each material as well as the properties found in the analysis and tests.

Inspection and Testing

Approval of the product will be considered based on factory inspections. When collecting price registration records for the first time, and for subsequent collections involving more than 20 items, valves of each diameter and pressure class must be tested. Inspectors may request sampling tests for the remaining items (as needed). All items will undergo visual inspection.

6.1 Hydraulic Test of Valve Chamber Cover (Certificate Issuance)

The valve must be completely filled with clean water that has passed the hydrostatic test and held under pressure for at least 10 minutes. No pressure drop shall occur during this period.

Note: Visual inspection will also be conducted during this period to detect possible leaks.

6.2 Disc and Seal Leakage Test (Certificate Issuance)

This test must last for at least 5 (five) minutes. Test pressure shall be applied downstream of the sealing disc, with the other side open to the atmosphere. For bidirectional seals, this operation shall be repeated on the other side. During the test, the valve must ensure that there is no liquid flow or dripping on the side open to the atmosphere, thereby confirming the complete tightness of the sealing disc. For the test of the body's tightness and mechanical resistance under pressure, the following method shall be adopted:

Table 2 - Leakage Test Guide

 

During the inspection, the equipment will undergo visual and dimensional inspection, as well as a hydrostatic test (for coated bodies), with a pressure of at least 1.5 times the nominal pressure applied. The pressure applied to the seals shall be at least 1.1 times the nominal pressure.

Pressure Reduction Test

The valve must be installed on a test bench equipped with calibrated pressure monitoring instruments (data loggers, pressure gauges, etc.), which are connected upstream and downstream. Then, the valve shall be subjected to the upstream nominal operating pressure to verify the corresponding pressure drop between the inlet and outlet.

Materials (Certificate Issuance)

The supplier must submit chemical analysis and mechanical test certificates for the materials used in the manufacture of the cabinet, cover, disk, stem, shutter, spring, and bushing. The certificates must allow traceability of the materials used by subcontractors and must include the specified properties of each material as well as the properties found in the analysis and tests.

Regulatory Reference Documents

The supplied products must comply with the latest versions of the following standards and documents:

NBR 15768 - Ductile Iron Butterfly Valves for Sanitary Purposes;

NBR 12218 - Design Procedures for Public Water Supply Distribution Networks;

NBR 7675 - Cast Iron Pipes, Fittings, and Accessories for Water Supply and Distribution Systems;

ASTM B584 - Standard Specification for Copper Alloy Sand Castings for General Applications;

ASTM A536 - Standard Specification for Ductile Iron Castings;

NBR NM 133 - Stainless Steel - Classification, Nomenclature, and Chemical Composition;

EN 558 - Industrial Valves - Face-to-Face and Center-to-Face Dimensions for Metal Valves Used in Flanged Piping Systems;

Appendix XX of the Consolidated Document No. 5 of the Ministry of Health;

NTS 299 - SABESP Technical Standard - Ball-Type Pressure Reducing Valves (DN 50 to DN 600).