THERMOVAC MEMS Vacuum Gauge Guide

Measurement range: standard 5 × 10 ⁻⁵~atmospheric pressure; It can be extended to 1 × 10 ⁻⁵~atmospheric pressure (RS 232/EtherCAT/display version) through a digital interface.

Applicable scenarios: automation integration, remote monitoring, data recording.

2.4 TTR 916 N (coated version with display screen)

Measurement range: 5 × 10 ⁻⁵~atmospheric pressure

Sensor: Coated MEMS Pirani (Parylene HT)

Interface: No digital interface, only analog output+2 set point relays

Display: Touch screen, displaying pressure, set point, status

Applicable scenarios: In corrosive processes, on-site display and local switch control are required

2.5 Special version: Long tube version

For applications that require higher chamber baking temperatures (such as UHV systems), provide a long tube version that separates the sensor from the electronic unit, keeping the electronic unit away from high-temperature areas. The sensor itself can withstand non operational baking at 85 ° C, and the electronic unit should be kept at 0-40 ° C.

Technical specification comparison

Parameters TTR 91 N/91 SN TTR 96 N TTR 911 N/911 SN/911 CN TTR 916 N

Measurement range (mbar) 5 × 10 ⁻⁵~1000 5 × 10 ⁻⁵~1000 5 × 10 ⁻⁵~1000 (standard); 1 × 10 ⁻⁵~1000 (digits) 5 × 10 ⁻⁵~1000

Sensor MEMS Pirani Coating MEMS Pirani/Coating (C) Coating MEMS Pirani

Measurement uncertainty 5 × 10 ⁻⁴~1 × 10 ⁻³: ± 10%;  1×10⁻³~100: ±5%; 100~Atmospheric pressure: ± 25% Same left Same left Same left Same left

Repeatability ± 2% (1 × 10 ⁻ ³~100 mbar) same left, same left, same left

Analog output Vout=log ₁₀ (P_mbar) × 1.286+6.143 (1.1~10 V) Same left, same left, same left

Number of designated points  0 (TTR 91 N) / 2 (TTR 91 SN) 2 2 (SN) / 2 (CN via Profibus) / 3 (SN via RS 232) 2

Digital interface None None RS 232/EtherCAT/Profibus None

Display screen without touch screen (911 N/SN/CN) touch screen

Power supply 9~30 V DC 9~30 V DC 9~30 V DC 9~30 V DC 9~30 V DC

Power consumption<1.2 W<1.2 W<1.2 W<1.2 W<1.2 W

Electrical Connection FCC68/RJ45 FCC68/RJ45 FCC68/RJ45 FCC68/RJ45

Working temperature 0~40 ° C 0~40 ° C 0~40 ° C 0~40 ° C

Baking temperature 85 ° C (non operating) 85 ° C (non operating) 85 ° C (non operating) 85 ° C (non operating)

Weight (DN 16 KF)~170 g~170 g~168 g (not shown)~170 g

Protection level IP40 IP40 IP40 IP40 IP40

Attention: All precision and repeatability data are typical values, measured using nitrogen at ambient temperature and obtained after zero adjustment.

Installation and electrical connection

4.1 Mechanical Installation

Installation direction: arbitrary. Due to the fact that MEMS Pirani sensors are not affected by gravity, the measurement signal is not sensitive to the installation position.

Vacuum connection: DN 16 ISO-KF is standard configuration, using centering rings and O-rings (Viton or other). The CF flange version is used for ultra-high vacuum systems.

Dead volume: approximately 2.8 cm ³ (DN 16 KF version), with minimal impact on system pumping time.

Baking: It can be baked to 85 ° C when not in operation. Note: The electronic unit should not be baked, and the long tube version can separate the sensor from the electronic unit.

4.2 Electrical Connections

All models use FCC68/RJ45 8-pin connectors (standard Ethernet cables). Pin definition (similar to TTR 101):

Pin 1: Power supply+(9~30 V DC)

Pin 2: Power supply GND

Pin 3: Analog output/Setpoint threshold output

Pin 4: Transmitter identification (identify model by resistance value)

Pin 5: Signal common terminal

Pin 6,8: Relay SP2 normally open contact

Pin 7-8: Relay SP1 normally open contact

Cable requirements:

Maximum length: 100 meters

Recommend using shielded cables (Leybold provides prefabricated 5-100 meter cables, part numbers can be found in the ordering information)

Shielding layer single ended grounding (on the controller side)

4.3 Power Supply and Grounding

The power supply voltage is 9~30 V DC, and 24 V DC is recommended.

Power consumption<1.2 W, can be powered by the controller or an independent power source.

The transmitter housing must be grounded through a vacuum system (KF flange using a metal clamping ring).

Simulation output characteristics and calibration

5.1 Logarithmic output formula

The analog output voltage of THERMOVAC transmitter is proportional to the logarithm of pressure (mbar):

Vout = log₁₀(P_mbar) × 1.286 + 6.143

The unit of Vout is volts. This formula is valid within the range of 5 × 10 ⁻⁵ mbar to 1000 mbar.

Theoretical output voltage of pressure (mbar) (V)

5×10⁻⁵ 0.61

1×10⁻⁴ 1.00

1×10⁻³ 2.29

1×10⁻² 3.57

1×10⁻¹ 4.86

1 6.14

10 7.43

100 8.72

1000 10.00

5.2 Integration with PLC

In PLC, the following formula can be used to convert voltage readings into pressure (mbar):

P_mbar = 10^((Vout - 6.143) / 1.286)

If using Torr units, the pressure value needs to be multiplied by a conversion factor (1 mbar=0.75 Torr).

5.3 Zero point adjustment

All THERMOVAC transmitters are calibrated at the factory. Zero drift may occur after long-term use, and it is recommended to regularly (annually) adjust the zero point. Adjustment steps (refer to a similar process in TTR 101):

Install the transmitter on the vacuum system and preheat it with power for at least 10 minutes.