Hydac EDS 34Z6-2-0400-G01-000 Flush-Membrane Pressure Switch

Flush-membrane switching for media that block a normal pressure port

The Hydac EDS 34Z6-2-0400-G01-000 (HYDAC part number 921476) is the flush-membrane version of the EDS 3400. The stainless steel diaphragm is level with the process connection, so viscous, dirty or freezing media cannot clog a bore, and residues do not remain to contaminate the next product. HYDAC lists this as the reason for the design.

The measuring cell is a thin-film strain gauge as in the standard EDS 3400. This code gives two PNP transistor switching outputs with a selectable analogue output, a four-digit rotatable display and a 400 bar range.

Technical specifications

Choosing the flush type

The standard EDS 3400 is the better value on clean hydraulic oil. Select the flush version when the medium is paste-like, crystallises, freezes or must be changed frequently, because there is no dead volume in the port. The trade-off is that the membrane needs careful handling: never push objects against it, and match the bore to the thread option you choose.

Code decoding

EDS 34Z6-2-0400-G01-000: Z denotes the flush membrane, 6 the M12x1 four-pole plug, 2 two switching outputs, 0400 the range in bar, G01 the G1/2 A DIN 3852 connection (G02 and G04 add a front O-ring, G12 a cooling section) and 000 the standard modification. The attached datasheet is the HYDAC USA flush-mount edition and lists psi ranges, so confirm the bar range and thread against your process. The earlier standard model is covered on our EDS 3400 page.

Where the medium is hot or sticky, ask the supplier whether the cooling-section option or a different seal is needed, because the standard fluid temperature limit is 80 °C. Torque the G1/2 A connection to 45 N·m with the correct seal, check the process temperature is within the 80 °C limit of this version, and flush the line before first start-up so that abrasive particles do not strike the membrane.

Flush membranes resist clogging in viscous and dirty media but are exposed at the process surface, so avoid mechanical impact during installation. Check that the thread seal and sensor depth suit the tapping in your tank or pipe before ordering.

Typical applications for the flush-membrane switch

The EDS 34Z6-2-0400-G01-000 is aimed at processes where a conventional pressure bore would sooner or later fill with product. Examples include hydraulic and process systems handling viscous fluids, pastes, media that crystallise or harden when they cool, and lines where the product is changed often and residues from one batch must not mix with the next. In these cases the flush stainless steel diaphragm sits directly at the process surface, so the pressure is measured where the medium flows instead of at the end of a narrow channel. Because this code combines two switching outputs with an analogue signal, a single instrument can both trip alarms or interlocks and give a continuous pressure value to the control system.

Selection considerations

Start with the medium. If the fluid is clean hydraulic oil, the standard EDS 3400 described on this page is usually the more economical choice; the flush version earns its place where clogging, hardening or contamination are real concerns. Next, compare the normal working pressure and any pressure peaks with the measuring range and the overload pressure in the table, so that the switch points sit within the useful part of the range. Then check the process temperature against the fluid temperature limit of this version, and confirm the mechanical connection and the tapping in the tank or pipe before ordering, because a flush membrane only works properly when the thread and the mounting bore match each other.

Integration with PLCs and control panels

The two PNP switching outputs can be wired to PLC inputs or relays to act as independent alarm and shutdown points, for example a warning level followed by a trip level. Hysteresis or window functions let the user choose whether an output resets after a fixed pressure drop or stays active only inside a defined band. The selectable analogue output, current or voltage, feeds an analogue input card or a panel indicator for trending. When the outputs are configured, record the set points, hysteresis values and analogue selection in the plant documentation so that a spare unit can be set identically later. Use screened cable on long runs and keep signal cabling apart from power cables to motors and drives.

Installation and service in Oman and the GCC

Plants in Oman and the wider Gulf region often expose instruments to high ambient heat, direct sun, dust and humid coastal air. The IP 67 protection class covers dust and water ingress, yet the switch should still be shaded where possible and kept within its operating temperature range, since outdoor skids and pipe racks can become very hot in summer. Protect the membrane during transport and fitting, tighten the connection to the specified torque, and flush new or modified lines before start-up so that welding debris and sand do not strike the diaphragm. During routine maintenance, inspect the membrane surface for deposits or mechanical marks and clean it gently, without tools that could scratch or dent it.

Documents and quotation

The datasheet is attached. Send the medium, the temperature and the code. See also our pressure instrumentation range.