Q&A


Questions regarding products (purchasing/use)


What is the difference in materials between type A and type B of wet gas meters?

Type A (brass) is mainly for general experiments, used for measuring inert gas.
Type B (SUS) has all contact areas made of stainless steel, making it suitable for active gases.


What is the difference between W-NK and WS?

The measuring drum is made of metal on W-NK, while WS has a resin drum.
If you focus on the flow rate, W-NK is best. WS is most suitable when the supplied gas has very low pressure.


What is the difference between wet and dry gas meters (precision, performance, gas compatibility)?

Dry gas meters are intended for simple measurement, and can be used immediately after installation.
Ill suited for moisturized gas, but with a wide measuring range, it can be used for a variety of measurements.
The DC model is lightweight and portable.
Wet gas meters are designed for high accuracy, and has excellent repeatability.


What kind of power supply do the gas meters use?

Both wet and dry gas meters operate on gas pressure (the difference between pressure at inlet and outlet). As such, they do not need any power supply for basic operation.


What are the points to consider when choosing between water and oil as sealing liquid in wet gas meters?

Compared to water, oil has little vaporization and volatilization, and as such can be used to measure for a long time without the need for replacement or replenishment.
For certain gases, water is recommended due to compatibility (especially for water-soluble gases such as hydrocarbon gas).
For short-term measurement and low frequency of use, water provides ample measurement capability. (Using oil means that there is generally no need to drain the sealing liquid.)


Regarding the use of pure versus tap water

Please use tap water for sealing liquid.
We do not recommend purified and ion exchanged water, as they can cause rust through electrochemical corrosion.


What should I do before a long period of disuse?

If the gas meter is to be put in long-term storage, regardless of if is a wet or dry meter, it should be purged with air to ensure that no gas remains.
For wet gas meter, please drain the sealing liquid, and make sure that the inside is dried out. (If oil is used as sealing liquid, draining is not necessary.)


Is correcting for deviation and temperature/pressure always necessary?

When you measure the variation over a certain period, please consider the effects from temperature and pressure.
When performing a one-time measurement, such as in a reaction experiment, there is no strict need to manage temperature and pressure. However, we recommend that measurements take place in a proper measuring evironment.
The gas volume changes 0.366% with a 1℃ temperature change, and 0.1% with a 100Pa pressure change. Please correct the result for influence from temperature and pressure.


Pulse output is currently being used with 0.01L/P. Can the frequency be higher than this?

W-NK-0.5, W-NK-1, DC-1 and DC-2 has 0.001L/P as a possible option.
Please contact us about other models, as this will be a special order.


The needle on a dry gas meter is moving jerkily. Is it broken?

The meter is not faulty. Measurement is done according to the movement of the diaphragm. At the changeover point, the movement is not smooth.
This is particularly noticeable with low flow.


When using a wet gas meter (measuring flow rate), the water level goes up and down. Why is this?

There can be some change in liquid level due to influence from the gas pressure. If there is a large variation, you likely have pulsation due to inconstant gas flow.
Please use a surge tank (cushion tank) or similar to stabilise the flow.
If the liquid level falls during measurement, this is caused by the pressure, not a faulty meter.


Using a wet gas meter, the needle moves slowly in about four places per rotation. Is the meter faulty?

As the structure is divided into four measuring chambers, the rotation changes slightly when it switches between chambers.


What should I do to determine if the meter is functioning properly?

First, please check that there are no loose connections or plugs, and conduct a leakage check.
If the model comes with a manometer, please use the manometer to conduct a leak test.
※You will find instructions for how to inspect the meter in the manual.
Also, please check for pressure loss within the flow range of each model. (See the product pages for specification.)
If the above steps show no fault, but you still suspect a defect, please contact us.


After purchasing a dry gas meter, variation in measurements appear after a while. Can it be exchanged for a new one?

All products are thoroughly tested before they are shipped from us, so you should first see if it could be due to external factors.
Please let the meter run idle for a while.
If the situation does not improve, please inform us of the details of your setup (connections, etc.), so that we can give you accurate advice.


When using the manometer, water is blown out. What should I do?

The attached manometer has a maximum pressure of either 1kPa or 1.8kPa. Kindly do not use the manometer outside of this pressure range.
If the pressure exceeds the range of the manometer, either use a 3.6kPa manometer, or a pressure sensor. (Both available as options)


When installing a DS meter, is a bypass line necessary?

To protect against damage from sudden pressure change, and to keep from having to close the gas line when disconnecting and connecting the meter (for e.g. repair or calibration), we recommend setting up a bypass line.


I want the pipe (diameter) to be narrower

As a narrower aperture will cause the characteristics to change, we kindly ask you to keep to the standard specifications.
If the change is unavoidable, please contact our sales department, which will help you to find a solution.
※In some cases, we will unfortunately not be able to comply with your wishes.


What is a bubbler?

It is a humidification unit used to reduce changes in liquid level in water-sealed meters.
If you use a bubbler, it will be easier to manage the liquid level if water is used as sealing liquid.


What should I keep in mind when using the meter?

To prevent a sudden pressure increase, please open the gas supply's valve slowly.
Also, please make sure that the outlet has not been obstructed.


What is the accuracy of the digital thermometer built into WS and DC meters?

±1℃


Please tell me the difference between Reference Standard meters and calibration meters

A Reference Standard meter qualifies as a Reference Standard in accordance with the Japanese Measurement Law, and so can be used to certify meters following this standard.
Calibration meters, while they can be used to calibrate other meters, do not qualify as Reference Standard, and so can not be used to certify meters.


The scale of the NK-2.5 and NT-25 shows a different volume than the drum volume. Is this a mistake?

For NK-2.5 and NT-25, one revolution of the indicator equates to two revolutions of the drum.


I want to change a counter's analogue output.

The user can change between 0-5V and 1-5V. For other changes, the counter would need to be returned to us.


I am planning to purchase an explosion-proof meter. What peripheral devices are available?

The intrinsic safety barrier is a required accessory. We can also provide a terminal box, but not the cable to connect the terminal box to the intrinsic safety barrier. Power supply for the safety barrier must also be handled by the user.


I am using a W-NK model. There is rotation when suction is applied, but not when gas is flown into the inlet.

The manometer might be open, or there might be a leak from the rod thermometer part. Please perform a leak test.


I am interested in a meter with the resettable counter. Can this be added to a meter I have?

This is possible. Please consider doing this concurrent with calibration or repair of the meter.


How much sealing liquid should be used in a wet gas meter?

Please adjust the liquid level so that it matches the tip of the needle in the liquid level gauge (on the right side of the meter when viewed from the front).


There is pulsating flow. How can I alleviate this?

Please use a cushioning device in the gas flow path, such as connecting a surge tank to the meter inlet.


Should I use gas temperature or liquid temperature when I correct the result?

If possible, please match the temperature. If there is a temperature difference, please use the gas temperature at the outlet for correction.


Is the measurement result influenced by the gas type?

The equipment measures the actual volume of gas flowing through it, and is unaffected by differences in density or specific gravity.


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