MKS 626A13TBE Baratron 626 Pressure Transducer

Technical Dossier

Product Details And Specifications

MKS Instruments Baratron 626 Series Technical Notes

The MKS Baratron 626 series is a capacitance manometer pressure transducer line manufactured by MKS Instruments, Inc. (Andover, MA, USA). It is one of the most widely deployed absolute pressure measurement solutions in global heavy industry and semiconductor process environments, including chemical vapor deposition (CVD) chambers, petrochemical refinery gas lines, nuclear facility inert gas monitoring systems, and pharmaceutical vacuum drying processes. The 626 series operates on the capacitance sensing principle, providing temperature-compensated, gas-species-independent pressure measurement across ranges from 1 Torr to 1000 Torr full scale. Its all-metal wetted construction (Inconel or 316L stainless steel diaphragm options) makes it the reference standard for corrosive and high-purity process gas applications. Installed base across global semiconductor fabs, chemical plants, and research institutions numbers in the hundreds of thousands of units, making long-term spare parts availability a critical operational concern.

The Evolution of Baratron 626 Architecture

The Baratron 626 series was introduced by MKS Instruments in the early 1990s as a successor to the 122 and 222 series capacitance manometers. The core architectural shift was the integration of a heated sensor head (standard at 45°C) to prevent condensation of process gases on the sensing diaphragm — a critical requirement for reactive gas environments in semiconductor manufacturing.

Generation 1 (626A / 626B, ~1992–2000): Established the standard 4-pin MS connector interface and analog 0–10 VDC output. The 626A suffix denotes Inconel diaphragm; 626B denotes 316L stainless steel. These units used discrete analog signal conditioning boards and are now fully obsolete with no OEM repair support.

Generation 3 (626E / 626F, ~2010–present): Current production generation. Features enhanced thermal stability, CE/SEMI S2 compliance, and compatibility with MKS Type 937A and 670 signal conditioner units. The 626F variant introduced a Hastelloy C-276 diaphragm option for HF and Cl₂ service. This generation maintains backward mechanical compatibility with 626A/B/C/D mounting flanges (VCR, KF, CF).

Compatibility note: All 626 series generations share the same 15-pin D-sub or 4-pin MS connector pinout for analog output, enabling direct substitution across generations in most process tool wiring harnesses. Digital output variants require signal conditioner firmware verification before substitution.

Baratron 626 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly stocked models within the MKS Baratron 626 series. Models are classified by diaphragm material, full-scale range, and output type.

Absolute Pressure Transducers — Inconel Diaphragm (626A prefix):

• 626A11TBE: 1 Torr full scale, Inconel diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626A12TBE: 10 Torr full scale, Inconel diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626A13TBE: 100 Torr full scale, Inconel diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626A14TBE: 1000 Torr full scale, Inconel diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626A11TBD: 1 Torr full scale, Inconel diaphragm, 45°C heated, 0–10 VDC output, KF-25 fitting
• 626A13TBD: 100 Torr full scale, Inconel diaphragm, 45°C heated, 0–10 VDC output, KF-25 fitting

Absolute Pressure Transducers — 316L Stainless Steel Diaphragm (626B prefix):

• 626B11TBE: 1 Torr full scale, 316L SS diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626B12TBE: 10 Torr full scale, 316L SS diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626B13TBE: 100 Torr full scale, 316L SS diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting
• 626B14TBE: 1000 Torr full scale, 316L SS diaphragm, 45°C heated, 0–10 VDC analog output, VCR fitting

Enhanced Generation (626C / 626D — Legacy Production):

• 626C11TBE: 1 Torr, improved EMI shielding, analog output, VCR, Gen 2 PCB architecture
• 626C13TBE: 100 Torr, improved EMI shielding, analog output, VCR, Gen 2 PCB architecture
• 626D13TBE: 100 Torr, optional RS-232 digital output, VCR, Gen 2 architecture

Current Production (626E / 626F):

• 626E13TBE: 100 Torr, CE/SEMI S2 compliant, enhanced thermal stability, VCR, current production
• 626F13TBE: 100 Torr, Hastelloy C-276 diaphragm, HF/Cl₂ service rated, VCR, current production
• 626F11TBE: 1 Torr, Hastelloy C-276 diaphragm, corrosive gas service, VCR, current production

Sourcing Hard-to-Find & Obsolete Baratron 626 Parts

The 626A and 626B generations entered end-of-life status with MKS Instruments between 2005 and 2012. The 626C and 626D series followed between 2015 and 2020. OEM factory repair and calibration services for these generations are no longer available through MKS Instruments' standard service channels.

Quality Control for the Baratron 626 Range

The Baratron 626 series presents specific quality verification challenges due to its capacitance sensing architecture and heated sensor design. Standard multimeter continuity checks are insufficient to verify transducer health. DriveKNMS applies the following test protocol to all 626 series units:

• Zero-point verification: Unit is evacuated to <1×10⁻³ Torr using a turbomolecular pump station. Zero output voltage is measured and compared against OEM specification (0.000 ± 0.005 VDC for 0–10 VDC output models).
• Full-scale calibration check: Controlled reference pressure is applied at 25%, 50%, 75%, and 100% of full-scale range using a primary pressure standard traceable to NIST. Output linearity is verified against OEM datasheet tolerance (typically ±0.25% of full scale).
• Heater circuit verification: Sensor head heater resistance and temperature controller setpoint are verified. Heater element continuity and thermal equilibration time (<15 minutes to 45°C ± 1°C) are confirmed.
• Diaphragm integrity check: Units are inspected for diaphragm deformation, corrosion pitting, and weld integrity at the process fitting interface using optical inspection and, where applicable, helium leak testing to <1×10⁻⁹ atm·cc/sec.
• Connector and cable inspection: All MS and D-sub connector pins are inspected for corrosion, bent contacts, and proper retention force. Cable jacket integrity is verified for units supplied with integral cables.