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The Guyco Ratio Type Pressure Reducing Valves are of fixed ratio type with ratios of 1.5:9 (3:2), 2:1, 3:1, 4:1 and 5:1, other combinations are available on request.

The valve is constructed of gun-metal and available with 316 stainless steel seat/piston and/pr PFTE coated piston and bore on request (3.2:1 etc).

It reduces pressure to the required ratio to protect appliances from damages caused by excess pressure. It also reduces surge and water hammer in pipelines.

Naturally, Guyco Valves are manufactured from high-grade materials under strict quality control conditions.

FEATURES:

• All gun-metal construction to BS1400 LG2 for both fresh and flush water applications
• Stainless steel BS970 seat, ring and piston
• Optionally with special wear resistant PTFE coating on bore and piston for flush water systems
• High grade synthetic rubber (NBR) for seat, ring and O-ring seals.
• Very reliable due to only one moving part that means only minimum maintanence is required
• Reduces both the static and dynamic fluid pressure to the required ratio regardless of the changes in inlet pressure and flow rate.
• Accurate control of pressure in service lines of fixed up-stream head situation, e.g. in high rise buildings or mines.
• Higher flow rate when compared with conventional spring loaded type pressure reducing valves.

SPECIFICATIONS:

Size Range:

Female screwed ends to BS21 -??

20mm (3/4”) to 65mm (2 ½”)

Flanged ends to BS4504 PN16 / PN5*

80mm (3”) to 150mm (6”)

*Optional with higher inlet pressure available on request.

Ratios Available: 1.5:1 (3:2), 2:1, 3:1 – other ratios to order.

Testing Pressure:

30 bar (3000kPa, 435 psi)

Operating Inlet Pressure:

• High rise buildings - flusherette, cold water and fire hydrants
• Mines
• Oil rigs
• High-pressure urban areas
• Mountainous terrain

SPECIFICATIONS & PERFORMANCE

Valve Selection - The Guyco valves are manufactured in accordance with BS EN 1567:2000. Valve selection should be determined by the pipe size, flanged and screwed thread details to the appropriate standards, desired ratios and where possible, the flow requirements. Specify =Body control size =Ratio =Flange size =Flange table =Thread standard

Ratio Selection - This is achieved by determining the inlet pressure at the entry to the valve and the desired outlet pressure. In fixed head situations, the inlet pressure can be easily calculated. Ratio accuracy to within plus or minus 5%. Once a valve has been specified, it is unlikely that it will need changing. However it is possible to alter the ratio by interchanging the piston and outlet spigot. This is a very simple process.

Flow Data
Flow is unaffected by ratio. Flow charts illustrated below were carried out by the Australian Irrigation Technology Centre (a NATA approved laboratory). Performance curves were produced while maintaining a fixed inlet pressure. N.B. For further details contact Guyco – email: sales@guyco.com.au

Operating Inlet Pressure
Minimum operating pressure – 200kPa (30psi) Maximum operating pressure – 3,500kPa (510psi)

Temperature Range
For cold water applications from 5°C (40°F) to 80°C (175°F)

Identification
All Guyco flanged valves and screwed valve 40mm and above, carry a serial number for traceability.

Assembly DetailsFor dimensions and parts list, refer to tables and illustrations.

DESIGN CONCEPT

With only one moving part – a piston – the Guyco Ratio Pressure Reducing Valve is perfection in its simplicity.

Configuration
The piston determines the ratio of the valve. Ratios can be altered simply by changing the piston and outlet spigot to the desired combination. i.e. 1.5:1 (3:2), 2:1 & 3:1. Higher ratios are obtainable if required, but not generally recommended as valve noise may be encountered. Other combinations are available on request; e.g. 3.2:1 or 2.4:1.

Sleek Design
Sleek design and superior fluid dynamics ensure minimal head loss through the valve. The cut away illustrations of the screwed and flanged valves in the open and closed position demonstrate the streamlined flow.

Body - Flange Series
The valve body has been manufactured from a copper based alloy – Type LG 2 to BS 1400.

Flange Series
Flexibility in manufacture enables flanges of various international standards to be accommodated i.e. BS 4504: section 3.3: 1989.

Body - Screwd Series
The 65mm screwed valves have been manufactured from a copper based alloy – type LG 2 to BS 1400. The 20mm – 50mm screwed valves are manufactured from DR brass.

Screwd Series
Flexibility in manufacture enabled thread forms of various international standards to be accommodated. Standard valves have threads manufactured in accordance with BS 21.

Inlet Spigot
Made from the same material as the body and has been designed with only three webs and shaped to minimise head loss.

Seat
Made from nitrile rubber. For potable water applications, materials used comply with BS 6920. If minor wear or damage occurs, it is possible to turn the seat over to extend its life.

Seat Retainer
Made from the same material as the body and has been designed in the shape of a reverse cone to increase the piston stroke in low flow conditions. This ensures long-term durability of the o-rings and minimises the risk of noise in high-pressure reduction situations.

Piston
Precision engineered for accuracy and manufactured from 316S31 stainless steel material in accordance with BS970; part 1. The piston face used in the flanged valves has been carefully machined to a pre-determined radius to minimise turbulence and eliminate noise emission during the opening and closing stages of the valve.

Outlet Spigot
Also made from the same material as the body, and is designed to suit the specific ratio. It can be simply changed over if required.

O-Rings and Seals
Manufactured from nitrile rubber in accordance with BS6920 and is suitable for potable water.

Special Coatings
The bore and pistons are available with PTEE(Teflon) coatings on request.

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