Overview
The DMM metering valve is a modular metering element for dual-line air-oil centralized lubrication systems. Each cycle meters an exact oil volume, which compressed air then propels to the bearing, gear or chain. Valves mount on a modular base of inlet, intermediate and end bases, so a single valve can be replaced without disturbing the rest of the line; see the dual-line lubrication systems guide for system background.
Four variants cover different discharge volumes: DMM and DM adjust on site through a graduated turret screw; DMF and DMMF are fixed-discharge versions. Blanking plates close positions reserved for future points.
Declared Specifications
| Parameter | Specification |
|---|---|
| Lubricant | Oil, 15-460 cSt viscosity; synthetic and biodegradable oils |
| Oil filtration | 25 microns or finer |
| Inlet connection | 3/8″ BSP or NPTF |
| Outlet connection | 1/4″ BSP or NPTF |
| Max inlet pressure | 400 bar (5,800 psi) |
| Operating temperature | -30°C to +80°C (-22°F to +176°F) |
| Air pressure | 1.5-3.0 bar |
| Cycle frequency | Up to 100 cycles/min |
| Adjustment | In-situ via graduated turret screw with lock nut |
| Body | Zinc-plated steel |
| Internal components | Tempered and ground steel pistons |
| Sealing | Metal-to-metal sealing, no gaskets required |
| Seals | NBR standard; FKM (Viton) for high-temperature duty |
Variants
| Model | Type | Discharge per cycle |
|---|---|---|
| DMM | Adjustable | 0.1-1.0 cc |
| DM | Adjustable | 0.25-3.0 cc |
| DMF | Fixed | 1.0 cc |
| DMMF | Fixed | 3.0 cc |
Adjustable models carry a graduated turret with an adjusting screw and lock nut, under a transparent cover or an aluminium cover. Fixed models need no adjustment.
How It Works
- Oil supply: pressurized oil enters through the 3/8″ inlet connection.
- Metering: the precision piston meters the exact oil volume for that cycle.
- Air injection: compressed air at 1.5-3.0 bar propels the metered oil toward the outlet.
- Discharge: oil is dispensed through the 1/4″ outlet to the bearing, gear or chain.
- Adjustment: on adjustable models, discharge volume is set via the graduated turret screw.
Installation
Valves mount on the modular base assembly, on a panel or custom brackets. Leave 50 mm clearance for service access. Supply clean, dry compressed air, and keep oil filtration at 25 microns or finer; poor filtration is the most common cause of sticking pistons. Threads are BSP or NPTF, specified with the order; blanking plates close unused positions.
Each valve normally has two free outlets. To convert to single outlet: remove the valve from the base, take out the inner O-rings on the unused side, reassemble with the outlet adapter oriented for single discharge, and plug the redundant port.
Applications
Typical uses are bearings, gear systems, chain drives and conveyors in steel mills and metal processing, cement and mining, pulp and paper, and heavy manufacturing. For steady oil flow control rather than dual-line air-oil metering, the oil flow control valve is the relevant product.
Maintenance
Maintenance is inspection-based, not calendar-based. Watch lubrication point condition for discharge consistency, replace seal kits when external leakage appears, and keep filtration at 25 microns or finer. Individual elements can be replaced without disconnecting the base or piping, so a faulty valve does not stop the system. Near the upper temperature limit, specify FKM seals rather than NBR.
Ordering Information
When ordering, specify model type (DMM, DM, DMF or DMMF), thread type (BSP or NPTF), number of metering elements, base assembly configuration (inlet base, intermediate bases, end base) and seal material (NBR or FKM). For a configuration review, request a quote with your system layout.
FAQ
What is a DMM metering valve and how does it work?
A modular valve for dual-line air-oil centralized lubrication systems. It meters a precise oil volume per cycle, and compressed air at 1.5-3.0 bar propels it to the lubrication point.
What is the difference between a dual-line and a progressive system?
A dual-line system uses two main lines and a reversing valve that alternates pressure between them, cycling every metering valve together; a progressive system meters lubricant through a divider in fixed sequence. The DMM is a dual-line air-oil metering valve, not a progressive divider.
What is the difference between DMM, DM, DMF and DMMF?
DMM covers 0.1-1.0 cc per cycle and DM 0.25-3.0 cc; both are adjustable. DMF and DMMF are fixed at 1.0 cc and 3.0 cc per cycle. All variants share the same base mounting dimensions.
How do I adjust the discharge volume?
On adjustable models, loosen the lock nut, turn the adjusting screw to the desired setting on the graduated turret, and retighten the lock nut – all in place, without removing the valve from the base.
Which lubricants are compatible?
Oil at 15-460 cSt at operating temperature, including mineral, synthetic and biodegradable oils. The valve does not deliver grease. NBR seals are standard; specify FKM near the upper temperature limit or with aggressive synthetic oils.
What are the pressure and temperature limits?
Maximum inlet pressure is 400 bar (5,800 psi). The operating temperature range is -30°C to +80°C (-22°F to +176°F).
Can I add valves to an existing system without shutting it down?
Yes. Install blanking plates at setup and swap in metering valves later; individual elements can be replaced without disconnecting the base or piping.
Can a valve be converted from two outlets to one?
Yes. Remove the valve from the base, remove the inner O-rings on the unused side, reassemble with the outlet adapter oriented for single discharge, and plug the redundant port.
How do I select the right model?
Calculate the oil volume each point needs per cycle. Small bearings and high-speed equipment suit DMM or DMF; larger bearings, gears and chains suit DM or DMMF. Choose an adjustable model if future changes are likely.
Who can review my configuration?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, can check your point count, volumes and base layout before you order. Write to inquiry@isohitech.com or contact us for a configuration quote.
