KELLER Series 35X Front-Flush Pressure Transmitter RS485

KELLER Series 35X combines a front-flush, seamless metal diaphragm with a digital RS485 interface and excellent accuracy: 0.05 %FS at room temperature and a total error band of 0.1 %FS over -10…80 degC. Ranges run from 0…0.3 to 0…1000 bar, and the pressure port is G1/2 front-flush, G3/4 front-flush or Tri-Clamp.

A flush diaphragm for viscous and hygienic-style process media

KELLER lists dosing systems, mixing systems, viscous media and the chemical industry as typical applications. With a flush diaphragm there is no pressure channel to block, and the front-flush body is seamless with no internal seals.

As with the other X-line transmitters, a Modbus RTU and KELLER bus interface on RS485 can be combined with an analog output that is re-rangeable (turn-down) through the digital interface. Digital resolution is 0.0005 %FS and the internal measurement rate is 1800 Hz or higher.

Key features as printed in the datasheet

• Front-flush AISI 316L diaphragm; connections G1/2, G3/4 and Tri-Clamp DN25-40 (1 to 1.5 inch).
• Accuracy 0.05 %FS; total error band 0.1 %FS at -10…80 degC.
• Long-term stability max. 0.1 %FS per year; yearly recalibration recommended.
• Media temperature -40…125 degC; ambient -30…85 degC.
• Optional Hastelloy C-276 wetted parts and other compensated temperature ranges.

Technical specification

Performance and electrical data

Mechanical and environmental data

Selection and ordering guide

Check the range table first: PR (vented, -1…range options available), PAA (absolute from vacuum) and PA (absolute from 1 bar) share ranges 0…1 to 0…1000 bar, with proof pressures from 3 bar up to 1100 bar. Ranges below 1 bar have their data referenced to a 1 bar full-range signal.

The Tri-Clamp connection has limited pressure ranges, so confirm the range and clamp size together. Alternative metals (Hastelloy C-276), O-ring materials and compensated temperature ranges within -40…125 degC are available on request.

Installation and operation notes

A flush diaphragm is damaged easily: the KELLER operating instructions for pressure transmitters say to leave the protective cap on until installation, avoid touching the diaphragm and handle flush connections with special care. The copper sealing ring must seat on a clean face.

Configure addresses, baud rate and analog scaling with the free CCS30 software via an RS485-USB converter, as KELLER describes for all X-line devices.

Applications in Oman and the GCC

Chemical dosing, polymer and additive blending, paint and resin lines, and viscous product lines are typical. In Gulf plants these include water-treatment dosing skids and food or beverage lines, where the Tri-Clamp option matches existing hygienic fittings. For high-temperature duty KELLER lists a separate 35HTX family with its own datasheet.

Compatible accessories and related items

KELLER lists Series 33X (standard port), 25Y (front-flush analog) and 35XHT (high temperature) nearby in the range. The 33X and 25Y are also listed on this site. Confirm the connection size, Tri-Clamp size where used, compensated temperature range and electrical connector in the datasheet before ordering, as these are configured per order.

Frequently asked questions

What is special about the 35X diaphragm?

It is a seamless front-flush metal diaphragm with no internal seals, so viscous media cannot collect in a port.

Which process connections does it offer?

G1/2 and G3/4 front-flush, and Tri-Clamp DN25-40 with limited ranges.

What interface does it use?

RS485 with Modbus RTU and the KELLER bus, optionally combined with an analog output.

What is the total error band?

0.1 %FS over -10…80 degC.

Is Seven Star LLC a KELLER distributor?

No. Seven Star LLC is an independent supplier in Muscat that sources KELLER products on request.

Documents and quotation

Download the official KELLER datasheet for 35X from this page. As an independent supplier based in Muscat, Seven Star LLC supplies KELLER items on request: use the quote form with the quantity you need. Check every value in the document against your own specification before you order. Browse similar items in the category.