GATHER Gear Flow Meter

Precise measurement technology for non-lubricating liquids

The GATHER gear flow meter (ZDM) is a volumetric flow meter based on the gearwheel meter principle for particularly non-lubricating, low-viscosity and chemically aggressive liquids. The movement of the gears is detected by a sensor via the individual gear teeth, in the form of pulses, contactless and hermetically decoupled. The GATHER ZDM is based on the same technology as the GATHER gear pumps which have seen decades of use in a wide variety of industries (including chemicals, pharmaceuticals, food, medicine, etc.).

Software functionalities

Downloads

Features

1. Measurement of non-lubricating liquids
2. High measuring accuracy
3. Large measuring range

4. Universal output signals
5. Robust design and long service life
6. CIP-capable

GATHER Gear Flow Meter

At a glance

1. Measurement of non-lubricating liquids

The combination of high-precision manufactured components and the use of chemically resistant materials is what makes volumetric flow measurement of non-lubricating, low-viscosity and chemically aggressive liquids possible in the first place. The housing and bearing pins are made of stainless steel, Hastelloy® or titanium.

2. High measuring accuracy

The high precision of the components and the double-disc design in combination with narrow gap dimensions and the smallest tolerance fields lead to a high accuracy of the measuring instrument. The combination of the newly developed linearity compensation and the user-adjustable viscosity adaptation for low-viscosity liquids improve the measuring accuracy up to the highest level. The sum of these features leads to a previously unattained accuracy in the field of measuring non-lubricating and low-viscosity media in gear flowmeters.

3. Large measuring range

One of the key advantages of this measuring system is, among other things, the large representable measuring range. For example, measuring spreads of up to 1:200 can be displayed. This makes the GATHER ZDM superior to many other flowmeters such as magnetic inductive flowmeters (MID) or Coriolis mass flowmeters (CFM). The low flow resistance, especially in applications with low-viscosity liquids, is an additional advantage of this wide-range measuring system for highly dynamic measuring tasks.

4. Universal output signals

In addition to a square wave signal output, the measuring instrument has standardized analogue outputs by default. The configuration settings can be easily made by the user. The calibration factor output is compensated and linearized by the software. This ensures a user-friendly integration into the user’s PCT. On delivery – but also after any subsequent factory calibration – there is only one device-specific calibration factor, which does not need to be adjusted during operation and which is furthermore constant over the entire measuring range.

5. Robust design and long service life

The high precision of the components as well as the double-disc design of the housing in combination with materials which have excellent tribological properties result in a very robust design and long service life.

6. CIP-capable

The unique design for this type of measuring tools enables CIP cleaning (CIP cleaning in place). Via the existing channels, rinsing processes can be carried out with suitable solvents and cleaning fluids in the installed state.

Software functionalities

Linearity compensation

Linearity, measement accuracy and repeatability are the decisive factors for a highly accurate measuring device. The linearity compensation implemented in electronics – unique on the market – enables the customer to operate the gear flow meter in the process with a linear and constant calibration factor characteristic curve – i.e. only one calibration factor over the entire measuring range. This is achieved by calculating the measurement signals determined during operation back in real time to the reference values corresponding to the factory calibration and thus compensating for them. The referenced measured values of the factory calibration are determined on the test bench using a calibrated high-precision measuring device and stored in the electronics. This reference measuring device is traceable to a national standard. The resulting calibration factor characteristic curve is therefore virtually ideal and has the same value at every potential measuring point. This makes operation very user-friendly in practice.
Viscosity adjustment

The volumetric measurement of low-viscosity media using a measuring device based on the positive displacement principle requires special measures. Especially in the range of very low viscosities, the corresponding medium has an increased influence on the volume flow to be measured and thus on the calibration characeristic. It may therefore be advisable to adjust the viscosity for certain applications in order to achieve maximum accuracy . GATHER gear flow meters offer the customer the option of carrying out the viscosity adjustment independently during the process. The different viscosity characteristics are determined during factory calibration and are stored on each device by default. The stored constant calibration factor is identical for each viscosity characteristic curve (internal conversion). This means that the customer does not have to adjust the calibration factor in the PCS if the viscosity characteristic curve is changed.
Pulse multiplication

Precise and accurate volume flow measurements require the highest possible resolution. With the customer’s individually selectable multi-stage signal multiplication , the maximum output frequency of the measuring device can be optimally adapted to the respective PCS. The maximum output frequency of the measuring device is 100 kHz. This functionality offers advantages for measuring, controlling and regulating in the lower flow range and therefore for metering small volumes.
Filter functionality

Fluid systems are subject to vibrations within a process. These vibrations are caused, for example, by pressure generators, body vibrations or fluid dynamic instabilities. The GATHER gear flow meter offers the possibility of damping these process-related vibrations by means of a filter functionality. The filter functionality can be activated or deactivated independently by the customer in the field. The filter functionality can have a positive influence on the control system behaviour , especially for demanding metering and control tasks.

GATHER Gear Flow Meter

Operating data at a glance

Characteristic	Property
Materials	Stainless steel, Hastelloy^®, titanium and special alloys
Liquids	Non-lubricating and lubricating liquids
Viscosities	0.6 to 2,000 cSt
Measuring ranges		See flow resistance characteristics
ZDM 01	0.05 up to 10 l/min
ZDM 02	0.1 up to 16 l/min
ZDM 03	0.15 up to 22 l/min
Temperature	T = –40 to +150 °C
Cleaning	Cleaning in Place (CIP)
Explosion classes	Zones 1, 2 inside , Zones 1, 2 outside T1 … T4