NDM
Rotary Gas Meter Installation and Operation Manual
Page 5of 13
Do not attempt repairs or adjustments, as doing so is a basis for voiding all claims for
warranty.
If the meter is not tested or installed soon after receipt, store in a dry location. Leave the
protective caps or tape installed at the meter flanges. The caps or tape will provide
reasonable protection against atmospheric moisture.
Do not add oil to the meter until after the meter has been installed in a permanent
installation and is ready for service.
When reporting a suspected problem, please provide the following information:
Your sales order number and/or NMTTM order number.
Meter model, serial number.
Description of the problem
Application information such as gas type, pressure, temperature and flow
characteristics.
Authorization for return is required for all NMTTM Products shipped to the Factory for
repair, calibration, warranty, exchange or credit. To obtain authorization for return of
NMTTM products purchased from an NMTTM Distributor of Representative, please
contact the Distributor or Representative from whom the product was purchased.
METER INSTALLATION
Reference Appendix A: The NDM rotary meters may be installed in either a Top/Bottom Inlet
(vertical) or a Side Inlet (horizontal) configuration. The preferred or recommended installation is
top inlet in a vertical pipe line with gas flow downward. Although the design of the impellers
tends to make the meter inherently self-cleaning, the top inlet mounting allows gravity to pass
dirt, pipe scale, or other debris trough the meter.
An additional recommendation is to install the meter in a side loop with a bypass adjacent to the
main line. Piping should be solid and properly aligned. Eliminate piping strains on the meter body.
Do not install the meter lower than the discharge pipe run to avoid accumulation of condensate
and foreign materials in the metering chamber. Use a Gasket Strainer or other V-type strainer
upstream of the meter to remove liquids and foreign matter (pipe sealant, tape, weld slag, etc.)
from the gas stream. A 100 micron mesh screen(gasket strainer or equiv.) is recommended.
Do not install a lubricated gas valve directly before a meter, as excess valve lubricant or other
foreign material can stop impeller rotation.
If over-speed conditions occur, a restricting flow orifice plate should be installed 2 to 4 pipe
diameters downstream of the meter outlet. Contact NMTTM for sizing.
