Rexroth DBET vs DBEM: Why Matching Pressure Is Not Enough
DBET-62/50G24K4V and DBEM10-71/315YG24K4M both provide proportional pressure control, but they serve very different flow duties. DBET handles small flows, including suitable pilot circuits. DBEM uses a pilot stage to control a main relief stage.
This comparison uses documentation for DBET series 6X and DBEM series 7X, matching the generations listed on our website. Numerical examples are illustrative.
Start with the flow through the valve
The DBET 6X catalogue specifies a maximum flow of 2 L/min, with additional restrictions for the 315, 350 and 420 bar pressure stages. It cannot carry a main relief flow of tens of litres per minute.
For DBEM size 10, the 7X catalogue lists a maximum of 275 L/min, with a separate 200 L/min limit for the threaded G version. The exact assembly, pressure conditions and fluid still govern selection.
Suppose a pump supplies 40 L/min and the circuit requires all that flow to pass through a proportional relief valve when the actuator stops. A valve rated for that duty is required. Increasing the pressure command cannot turn a 2 L/min DBET into a 40 L/min main relief valve. Pressure may escape the intended control range, another protective device may operate, or the machine may stop.
A pilot branch carrying 0.8 L/min is a plausible DBET application. Its selected pressure stage, flow curve, amplifier and drain arrangement still need checking.
Pressure stage and inlet rating are separate
The 50 in DBET-62/50 identifies a 50 bar pressure stage. A family inlet-pressure rating of up to 420 bar does not make this version a 420 bar adjustable pressure valve.
The 315 in DBEM10-71/315 identifies a 315 bar pressure stage. The referenced 7X documentation lists a maximum operating pressure of 350 bar at P and X; the ordered assembly and nameplate remain controlling.
| Check | DBET 6X | DBEM 7X |
|---|---|---|
| Construction | Direct-operated | Pilot-operated with main stage |
| Listed example pressure stage | 50 bar | 315 bar |
| Flow capability | Up to 2 L/min; restrictions at some pressure stages | Size 10 up to 275 L/min; G version 200 L/min |
| Electronics | External amplifier | External amplifier |
| Corresponding integrated-electronics family | DBETE | DBEME |
A 24 V designation does not establish proportional control
Both listed models require a compatible external amplifier. G24 is not permission to apply a switched 24 V supply and expect PLC-controlled pressure. Verify command format, coil-current rating, output limits and enable conditions.
If the PLC command rises but measured amplifier current remains unchanged, an unchanged pressure is consistent with an electrical output limit. Mechanical adjustment will not restore a missing current response.
If current follows the command but pressure is too high, check the drain arrangement as well as supply pressure. Follow the specified separate, low-pressure return arrangement for DBET T/Y and DBEM Y. Return resistance can affect pressure control.
Check the mechanical pressure limit separately
The M in DBEM identifies a mechanical maximum-pressure limitation. Its intended protection against pilot-control faults does not replace every protective function required by the machine. Verify its setting and applicable flow duty.
Keep the complete model, amplifier configuration, pressure settings and circuit drawing before replacement. Acceptance should confirm command-to-pressure response at the required flow and the maximum-pressure limitation.
Select relief-flow capacity before selecting the pressure stage. DBET and DBEM cannot be exchanged on pressure range alone.