Pressure sensors and Liquid leak sensors FAQ
Pressure sensors and Leakage sensors FAQ
- Chapter 1
- About Products (1)
Q1. About cable specifications
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We want to fit a connector to a cable. Where can we find your cable specs?
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For cable specifications for various pressure sensors, refer to the cable core diameter table.（PDF）Cautions for when crimping contact pins
- 1. Select the correct conductor size and contact pin size recommended by the manufacturer.
- 2. Strip the conductor insulation to the length specified by the manufacturer.
- 3. Use the crimping tool recommended by the manufacturer.
Q2. Scope of non-corrosive gases in medium
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You require that a pressure medium for use with P-2000 or P-3000S should be a non-corrosive gas. Can steam-laden air be used? If not, what model do you recommend?
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The P-3000S is designed to have a sensor chip in direct contact with the medium. Exposure to moisture will affect the characteristics of the sensing chip. Meanwhile, the PA-800 dual-diaphragm transducer is built to receive pressure with its stainless steel diaphragms and transmit the pressure via the sealed-in silicone oil, so that it can measure the pressure of steam or that of a liquid. Models of pressure transducers usable with steam-laden air include P-8300 and P-8505 (with no amplifier) as well as PA-750/758 and PA-830/838 (with an amplifier). Our recommended models of pressure switches include PS83 and PS85. Our recommended models of pressure gauges include PG-35 and PG-75. For more detailed information, refer to the section on the pressure media in the Product Guide.
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P-3000S Internal structure
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PA-800 Internal structure
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Q3. How to clear noises (Wiring shield cable)
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The transducer we use has a built-in amplifier. Its output fluctuates, and the cause seems to be noise. The side for mounting to the equipment is insulated. The shielding wires on the receiver side are not connected to anywhere during use. What measures should be implemented?
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The FG is insulated on both the equipment side and the receiver side, which suggests that noise propagation through the cables caused the output to fluctuate. Ground the shielding wires on the receiver side to reduce the influence of the noise.
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(a) Sensor is earthed
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(b) Sensor is insulated
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Q4. How to set switch of pressure switch
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We intend to use a KF25 flange fitting for a PS91 vacuum switch for atmospheric pressure monitoring to detect when a vacuum heating oven is under atmospheric pressure. We are not sure how to select N1 and N2 and would like your advice. We imagine that the vacuum switch turns on when the pressure returns from vacuum to atmospheric pressure. How should the switch output be selected and set so that the vacuum switch turns on at -80 kPa when the pressure goes from atmospheric pressure to a vacuum?
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In the case of an N1/P1-type PS91 switch, both SW1 and SW2 turn ON when the pressure rises. In the case of the N2/P2 Type, SW1 turns ON when the pressure drops, whereas SW2 turns ON when the pressure rises. For a configuration in which the SW turns ON when the pressure returns from a vacuum to atmospheric pressure and when the pressure goes from atmospheric pressure to -80 kPa, select the N2/P2 Type.
PS91 N2/P2 type switch output operation
Next, let us see how to set the switch. Before starting, prepare a PS-91-102V-N2-K2, a digital manometer, a pressure-regulating valve, a vacuum pump, a constant-voltage power supply, and a trimmer adjustment precision screwdriver. Be sure to connect the lead cables of the PS91 correctly to the power supply: the red lead cable is for connection to the plus side of the power supply, and the black lead cable is to be used as the common return cable. Set the power supply to the same voltage as that of the equipment. Then, connect the digital manometer to the pressure-regulating valve between the PS-91 and the vacuum pump according to the piping drawing below. First, let us set the SW to turn ON when atmospheric pressure is reached. With the vacuum pump OFF, adjust the pressure on the PS91 to atmospheric pressure. The operation mode of the SW2 of the PS91 is such that it turns ON when the pressure rises. In other words, the point at which the operation indicator LED comes on when the pressure setting trimmer 2 on the backside is turned clockwise is the point at which SW2 turns ON when atmospheric pressure is reached. Then, with the pressure-regulating valve opened, turn the vacuum pump ON and look at the digital manometer to make sure that the vacuum is reached. After that, turn OFF the vacuum pump and vent it to the atmosphere. Make sure that the operation indicator LED of the PS91 comes on when the digital manometer reads 0. Next, let us set the SW to turn ON when the pressure drops from atmospheric pressure to -80 kPa. First, with the pressure-regulating valve closed, turn the vacuum pump ON. Open the valve gradually to adjust the pressure to -80 kPa. The operation mode of the SW1 of the PS91 is such that it turns ON when the pressure drops. In other words, the point at which the operation indicator LED comes on when the SW1 on the back is turned clockwise is the point at which the switch turns ON when the pressure reaches -80 kPa. After that, turn OFF the vacuum pump and allow the pressure to return to atmospheric pressure. After seeing that the pressure has returned to atmospheric pressure, close the valve and turn ON the vacuum pump. Open the pressure-regulating valve gradually and make sure that the operation indicator LED comes on when the digital manometer reads -80 kPa. The knack for pressure setting is adjusting the pressure setting trimmer and the pressure-regulating valve slowly.
Q5. Mounting on PCB (Manual soldering required)
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We want to solder a P-2000 onto a printed circuit board. What are your recommended soldering conditions?
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For our recommended soldering conditions for different types of sensors available from us, refer to the Recommended Soldering Conditions Table.（PDF）。Cautions for soldering
- 1. Install a PCB-mountable P-2000, P-3000S, or PA-100 onto a PCB by hand-soldering instead of flow-soldering or reflow-soldering.
- 2. Remove flux residues not by immersion in the cleaning liquid but by wiping with a cleaner-soaked cloth.
- 3. Take care and prevent any flux, cleaning liquid, or desiccant from entering the inside of the sensor or getting into the vent hole.
- 4. After the pressure ports and the terminals are mechanically positioned so that no mechanical force is applied to them, solder the terminals to the PCB.
Q6. Recommended fittings for M5 female screws connecting tubes
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We want to connect a pressure sensor to its tube using an M5 female screw. What attachment do you recommend?
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For our recommended fittings for connecting pressure sensors to urethane/nylon tubes, refer to the following table.
Manufacturer's name Application（Manufacturer's name） Tube decimations (mm) φ4 (4×2.5) φ6 (6×4) Koganei Co., Ltd. Quick fitting TS-4-M5 TS-6-M5 Quick fitting TS-4-M5M TS-6-M5M TAC fitting BF4 BF6 Nihon pisco co. ltd Tube fitting PC4-M5 PC6-M5 Tube fitting PC4-M5M PC6-M5M Tube fitting minimal LC-0425-M5 LC-0640-M5 ※If you have any questions about the specs of the fittings, such as detailed dimensions, directly ask the manufacturers shown in the table.
Q7. Recommended tubes for quick fittings
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What tubes do you recommend for use with the quick fittings?
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For our recommended urethane/nylon tubes, refer to the following table.
Manufacturer's name Tube type（Manufacturer's name） Tube decimations (mm) φ4 (4×2.5) φ6 (6×4) Koganei Co., Ltd. Nylon tube N4B N6B Urethane tube U4 U6 nihon pisco co. ltd Nylon tube NA0425 NA0640 Urethane tube UB0425 UB0640 ※(If you have any questions about the specifications for the tubes, such as maximum operating pressure, directly ask the manufacturers shown in the table.)
Q8. How to installate to piping (Tightening torque)
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What tightening torques do you recommend for tapered screw types?
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For tightening torques, refer to the table below. If your fitting is a tapered screw type, wrap sealing tape around the threaded portion and screw the fitting into the matching pipe. When doing so, leave about two threads bare from the end of the threaded portion. Do not start wrapping right at the end of the threaded portion. Failure to comply may result in the dropping of torn pieces of sealing tape into the pipe. Press the wrapped sealing tape down and adapt it to the threads before screwing the fitting into the pipe. The tightening torques shown in the following table are for rough reference only.
Take into consideration such factors as the material of the fitting to set the optimum value.
(Fig.)
Screw shape Tightening
torque(N·m)R 1/8 7 ~ 9 R 1/4 12 ~ 14 R 3/8 22 ~ 24 M 5 1.0 ~ 1.5
Q9. Effect of vertical to horizontal installation position
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The dual-diaphragm pressure sensor we use varies in output depending on whether the pressure port is turned downward or sideways. Does this mean the sensor is out of order?
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Our dual-diaphragm pressure transducer contains sealed-in silicone oil, and its output varies when its sensor element detects the weight of the silicone oil. If stable in its installed position, the transducer shows constant output. The influence of the installed position varies depending on the model and pressure range of the transducer. Refer to the brochure for details.e.g. Internal structure of P-8300 pressure transducer
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Part name Material ①Sealed liquid Silicone oil ②Sensor chip Silicone ③Stainless steel diaphragm SUS316L ④Compensation resistor board Ceramic ⑤Vent hole (Gauge type only) Iron+gold-plated ⑥Pressure port SUS316L ⑦Terminal pin Copper+gold-plated
Q10. Stability after power applied
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According to the Common Notes, a warm-up time of about 10 minutes after power-on allows more accurate measurement. How much does the output voltage [V] fluctuate during the 10 minutes after power-on? We also want to know whether the output voltage changes linearly or not.
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After power-on, the zero point shifts and stabilizes in about 10 minutes, as shown in the chart below. Hence, a warm-up time of about 10 minutes after power-on ensures more stable output and hence allows more accurate measurement. The chart below is for reference only.Fig.) Stability of zero point after power on（Product ratio of our company）
※Refer to the chart（The direction and magnitude of shifting vary depending on the product.)
Q11. Products selection suitable for using high vacuum
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We have adopted the PA-850-102A-NR2 to monitor the internal pressure of a vacuum chamber. Our process requires pressure reduction to an absolute pressure of approx. 0 kPa. The brochure specifies a lower limit of operating vacuum of 1.3 kPa abs. Why is it unusable beyond this value? Recommend pressure sensors usable beyond the value.
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Long-term use in a high vacuum may lead to a shift in the output of our dual-diaphragm pressure transducers because of air trapped within the silicone oil. Therefore, a lower limit of operating vacuum of 1.3 kPa abs is specified. We offer silicone oil-free, thin-film element pressure transducers as high vacuum-compatible products. See the table on the right side below:
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A. Double diaphragm(Oil-enclosured) type
Series name Pressure lower limit P-8300, P-8305, P-8505, PA-750, PA-758, PA-800, PA-830, PA-838, PA-838-D, PA-840, PA-848, PA-850, PA-858, PS8, PS83, PS85, PG-35,PG-75, PG-208, PG-100B 1.3 kPa abs. -
B. Thin film type(High vacuum compatible)
Series name Pressure lower limit PA-920S, PA-928S, PA-930, PA-930-A, PS91, PG-20, PG-35L 1.4 × 10-4 kPa abs.
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Q12. About operating temperature range of medium
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What is the liquid temperature range applicable to the PG-35? Although we are currently using room-temperature water, we want to use heated water and hence have to know the liquid temperature range.
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The liquid temperature range applicable to the PG-35 is the same as the operating temperature range of -10°C to 50°C. The operating temperature range varies depending on the model. Refer to the Product Guide for details.（PDF）
We may be able to recommend a wider temperature range depending on the applicable use conditions. Check with our sales office, sales agent, or authorized sales distributor in your area.
Q13. Effect of accuracies by ambient temperature
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How come the PG-100B has two different system accuracies, one being ± 0.5% F.S. ± 2 digits and the other being ± 1.0% F.S. ± 2 digits?
Besides, what does "± 2 digits" mean? -
While ± 0.5% F.S. ± 2 digits (25°C ± 5°C) is the level of accuracy within the rated pressure range at a constant ambient temperature of 25°C, ± 1.0% F.S. ± 2 digits (25°C ± 25°C) is the level of accuracy within the rated pressure range under ambient temperature ranging from 0 to 50°C.
The value ± 2 digits means that the lowest digit of the reading includes ± 2 digits' worth of errors.
Q14. Rated pressure range / Max. pressure / Break pressure
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What does the rated pressure range and maximum pressure in the specification mean?
Will the sensor be broken if the burst pressure value is exceeded? -
The rated pressure range is a range of pressure by which we guarantee the specifications of the pressure sensor. The maximum pressure is the largest value of pressure that you can apply to the pressure sensor. After the application of the maximum pressure beyond the rated pressure, the specifications are guaranteed within the rated pressure. Note, however, that the offset voltage, the zero voltage, and the zero current may change. The "burst pressure" means the pressure value at which electrical or mechanical destruction occurs to the pressure sensor. Caution is advised in this case because the pressure medium under measurement is very likely to leak out.
Q15. How to purchase lithium batteries for PG-100
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The replacement battery specified for the PG-100 manometer is a lithium battery 3.6 V DC. The battery originally supplied with the PG-100 is one manufactured by Toshiba and bearing the model number ER6VM/3.6, which cannot be found on Toshiba's website, although ER6V P3.6 is found there. Is it OK to use the latter instead?
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The only lithium battery usable with the PG-100 is ER6VM/3.6, manufactured by Toshiba Lifestyle Products & Services Corporation. ER6VM/3.6 is not available off the shelf. To purchase it, contact our sales office, sales agent, or authorized distributor in your area and inform of the model name “Lithium Battery (for PG)”. The used battery must not be disassembled, short-circuited, recharged, thrown into a fire, heated, or tampered with in any other way. Dispose of the used lithium battery according to the regulations applicable to your area. When not to be used for a long period, remove the battery from the manometer and store it in a dry, cool place.
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