In industrial process measurement and control, manifold valves serve as core supporting components for pressure, differential pressure, flow and level transmitters. They perform critical functions including medium isolation, pressure balancing, venting and draining, as well as on-site calibration, directly determining the stability, safety and maintainability of measurement systems. Featuring integrated structure, complete configurations and stringent quality standards, Emerson Rosemount 304/305/306 series manifold valves are widely adopted across global industrial sites. This article comprehensively illustrates their working principles, core advantages, application scenarios and operational specifications.
Product Overview: Three Series Covering Full-range Applications
All Rosemount 304, 305 and 306 manifold valves are factory-assembled products with leakage inspection and calibration completed in advance. Classified into integrated, direct-connected and conventional types, they match diverse transmitter structures and mounting requirements.
| Model |
Type Positioning |
Main Connection Mode |
Compatible Transmitters |
| 305 Integrated Manifold |
Coplanar & traditional flangeless direct mounting |
NPT internal thread, no flange required |
3051 / 3051S coplanar differential pressure and multivariable transmitters |
| 306 Direct-connected Manifold |
Compact threaded connection |
NPT internal & external thread |
Direct-connected pressure transmitters, wireless pressure gauges |
| 304 Conventional Manifold |
Traditional flange connection |
Flange to flange, flange to NPT |
Traditional flange-type transmitters, optional thin-plate design |
Working Principle: 2/3/5-valve Configurations for Accurate Isolation & Balancing
Multiple valves work collaboratively to realize four major operations: medium isolation, pressure balancing, venting & draining, and on-line calibration. Different valve quantities cater to distinct working conditions.
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2-valve Manifold (Gauge & Absolute Pressure Measurement)
Structure: 1 isolation valve + 1 vent/drain valve
Working principle: The isolation valve cuts off the connection between process medium and instrument pipeline. The vent/drain valve empties pipelines and supports instrument calibration, applicable for gauge and absolute pressure transmitters.
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3-valve Manifold (Standard for Differential Pressure Measurement)
Structure: 2 isolation valves + 1 balance valve
Working principle: Two isolation valves control high-pressure and low-pressure process ports respectively. The balance valve connects high and low pressure chambers to achieve zero balance and prevent diaphragm damage caused by excessive differential pressure. It is the standard configuration for differential pressure and flow measurement.
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5-valve Manifold (High-precision Differential Pressure & Multivariable Measurement)
Structure: 2 isolation valves + 1 balance valve + 2 vent/drain valves
Working principle: Based on 3-valve structure, additional bilateral independent discharge ports enable controllable full-process venting, draining and on-site calibration, ideal for natural gas and high-precision industrial processes.
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Special 5-valve Design for Natural Gas
Dual balance valves are equipped to enhance leakage prevention. Wide handles, soft valve seats and large-bore passages reduce clogging risks, meeting strict requirements of natural gas metering.
Core Features: Safety, Reliability & Easy Maintenance
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Integrated Structure Greatly Reduces Leakage Points
305 integrated manifolds adopt flangeless direct connection, cutting leakage points by 50% compared with conventional flange connection designs. The compact and lightweight structure fits both vertical and horizontal process piping installation.
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Qualified Materials with Superior Corrosion Resistance
Wetted parts are mainly made of 316/316L stainless steel, with optional Alloy C-276 and Alloy 400. Certified by NACE MR0175/ISO 15156, the valves adapt to sour gas and corrosive service conditions.
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Wide Pressure & Temperature Tolerance for Severe Environments
Maximum pressure rating: 689 bar (10000 psi)
Operating temperature range: -18℃ ~ 538℃
Combination of PTFE/graphite packing and integrated/soft valve seats ensures stable performance from low to high temperature scenarios.
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Pre-assembled & Pre-calibrated for Plug-and-play Use
Factory assembly, tightness testing and calibration are finished beforehand. On-site installation can be implemented directly, shortening construction duration and minimizing assembly errors.
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User-friendly Maintenance with On-line Calibration Support
Zero adjustment, medium drainage and equipment inspection can be carried out via drain and balance valves without removing transmitters, effectively reducing system downtime.
Typical Application Scenarios
Oil & Gas Industry
Applied in oil and gas exploitation, gathering, transportation and metering. The dedicated 5-valve structure guarantees measuring accuracy and operational safety under sour gas and high-pressure conditions.
Chemical & Refining Industry
Suitable for pressure, differential pressure and flow measurement of high-temperature, high-pressure and corrosive media. Corrosion-resistant materials and reliable sealing deliver stable performance.
Power Generation
Comply with ASME B31.1 power piping codes. Widely used in steam, water and oil systems for monitoring boilers and heat exchange equipment.
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