HMA Instrumentation offers a range of quality differential pressure gauges designed to measure the difference in pressure between two points in a system. The gauge range from HMA Instrumentation is available in various sizes and materials, including Monel, brass, and stainless steel.

Rototherm Light to Medium Duty Differential Gauges

Rototherm’s quality differential pressure gauges from HMA Instrumentation are designed to measure the difference in pressure between two points in a system and to display it on a single dial gauge. A magnetic movement senses the differential pressure. The gauges have separate pressure and indicating chambers.

These diaphragm instruments can indicate minute differential pressure values, even when used at high line pressures. They provide instantaneous and continuous information regarding system conditions, assisting in eliminating premature servicing of equipment, avoiding unscheduled downtime of costly processes, and detecting any abnormal system conditions.

Rototherm’s quality differential pressure gauges from HMA Instrumentation can be supplied with reed switches to initiate alarms, activate other equipment, or to shut the system down completely if required. Two switches are used when high and low limits are desired. Gauge switch models provide the user with both gauge readout and switch operation.

Applications range from monitoring filter conditions to setting filter by-pass, initiating a filter cleaning cycle, determining any obstructions in process lines, checking the condition of pumps, heat exchangers and other processing equipment, adjusting flow rates in piping systems, and monitoring liquid levels in storage tanks.

Rototherm 200DGR Differential Pressure Gauge

• Accuracy: ±2% of the FSD (Ascending)
• Migration: No migration, zero leakage from high to low port
• Range: 0-0.25 to 0-7 bar (or equivalent ranges in other units)
• First marking on the scale: 15% of the FSD
• Wetted parts: Diaphragm, body material SS 302 spring and ceramic magnet
• Case material: Stainless steel Grade 304
• Dial size (mm): 50, 63, 80, 100, 115, 150
• Mounting: Direct, front flange, 2″ pipe and surface mounting
• Maximum working pressure: 200 bar/3 000 psi
• Maximum process temperature: 80°C
• Body material: Aluminium, brass and SS 316

Rototherm 200DPG Differential Pressure Gauge

• Accuracy: ±2% of the FSD (ascending)
• Migration: Minor (from high to low port)
• Range: 0-0.25 to 0-70 bar (or equivalent range in other units)
• First marking on the scale: 20% of the FSD
• Wetted parts: Body material SS 302, spring, ceramic magnet and seals
• Case material: Stainless steel Grade 304
• Dial size (mm): 50, 63, 80, 100, 115, 150 mm
• Mounting: Direct, front flange, 2″ pipe and surface mounting
• Maximum working pressure: 200 bar for aluminium and brass, 400 bar for stainless steel and Monel
• Maximum process temperature: 80°C
• Body material: Aluminium, brass, SS 316 and Monel

Rototherm 300DGC Differential Pressure Gauge

• Accuracy: ±2% of the FSD (ascending)
• Migration: No migration, zero leakage (from high to low port)
• Range: 0-0.075 to 0-4 bar (or equivalent ranges in other units)
• First marking on the scale: 15% of the FSD
• Sensing element: Diaphragm
• Wetted parts: Diaphragm, body material SS 302, spring and ceramic magnet
• Case material: Stainless steel Grade 304
• Dial size (mm): 63, 80, 100, 115, 150 mm
• Mounting: Direct, front flange, 2″ pipe and surface mounting
• Maximum working pressure: 100 bar/1 500 psi
• Maximum process temperature: 80°C
• Body material: Aluminium, brass and SS 316
• Rototherm 400DGC Differential Pressure Gauge
• Accuracy: ±2% of the FSD (ascending)
• Migration: No migration, zero leakage (from high to low port)
• Range: 0-25 to 0-600 mm H2O (or equivalent ranges in other units)
• First marking on the scale: 15% of the FSD
• Sensing element: Diaphragm
• Wetted parts: Diaphragm, body material SS 302, spring and ceramic magnet
• Case material: Stainless steel Grade 304
• Dial size (mm): 80, 100, 115, 150 mm
• Mounting: Direct, front flange, 2″ pipe and surface mounting
• Maximum working pressure: 35 bar/500 psi
• Maximum process temperature: 80°C
• Body material: Aluminium and SS 316

Rototherm 600DGC Differential Pressure Gauge

• Accuracy: ±3% of the FSD (ascending)
• Migration: No migration, zero leakage (from high to low port)
• Range: 0-25 to 0-1250 mm H2O
• First marking on the scale: 15% of the FSD
• Sensing element: Diaphragm
• Wetted parts: Diaphragm, body material SS 302, spring and ceramic magnet
• Case material: Stainless steel Grade 304
• Dial size (mm): 112 mm
• Mounting: Flush (standard), 2″ pipe and surface mounting (upon request)
• Maximum working pressure: 2.4 bar/35 psi
• Maximum process temperature: 60°C
• Body material: Engineering polymer

Rototherm DP3 Differential Pressure Gauge

The Rototherm DP3 Differential Pressure Gauges from HMA Instrumentation comprise a range of economically-priced 100 mm and 150 mm nominal size Differential Pressure Gauges ideal for most medium- to heavy-duty industrial applications where accuracy and durability are vital.

HMA Instrumentation also provides a selection of mounting options to enable simple installation. These include either direct mounting to the process, in a panel, surface mounting on a wall, or with a vertical or horizontal pipe mounting. DP360, DP370 and DP362 instruments all feature electrical contact head options and can be fitted with diaphragm seal units.
The Rototherm DP range of Differential Pressure Gauges offers options such as Monel 400 and Hastelloy C276 wetted parts, and oxygen cleaning and liquid-filled cases. Three- and five-valve integral and remote mounted manifolds are also available.

Rototherm DSU Diaphragm Seal Units

HMA Instrumentation recommends to fit a Rototherm DSU Diaphragm Seal Unit to a pressure gauge where the medium to be measured is highly viscous, contains suspended solids, or is potentially corrosive to the Bourdon tube. Rototherm DSU Diaphragm Seal Units from HMA Instrumentation are normally connected directly to the gauge. However, the connection may be also be affected by flexible capillary, which makes them ideal for remote pressure indication.

The flexible capillary can be used to facilitate the fitting of a Rototherm DSU Diaphragm Seal Unit from HMA Instrumentation in a surface- or panel-mounting location. The maximum capillary length is 5 m. Pressure is transmitted from the Rototherm DSU Diaphragm Seal Unit to the Bourdon tube by means of a suitable filling medium, the selection of which ensures compatibility with the process and process temperature.

If the Rototherm DSU Diaphragm Seal Unit from HMA Instrumentation is to be used on processes subject to temperature extremes, the temperature at the tipping point should be advised at the time of ordering. Rototherm DSU Diaphragm Seal Units from HMA Instrumentation can be fitted directly or remotely to the following Rototherm gauge types: SPG, RPG, DMC, SPGA, and turret gauges.