Measuring Gas Velocity with the D-FL 100 Differential Pressure Bar

D−FL 100 Seite 247. MaintenanceThe D-FL 100 is a low-maintenance system with long maintenance intervals. The maintenance scheduledepends on the application, and is generally several months (3 months as a rule of thumb). Pressureconditions, climatic and other ambient influences at the measuring site, and the gas being measured allaffect the maintenance schedule.Maintenance work should be performed in the following order:1. Adjust menu item Maintenance at the D-FL 100-10 Display.Use the MOD key on the D-FL 100-10 Display to select Stand by.2. Clean the exterior of the unit.3. Check the differential pressure bar and the differential pressure transducer.Check exterior covers and the connections between differential pre ssure bar and transducer.4. Flush the measuring pipes.The pipes may need to be flushed, depending on application conditions. By changing the setting ofthe switching valve, purge air is directed separately to the different pressure lines (see Fig. 4 forswitching valve settings).5. Clean the differential pressure bar.Under extreme application conditions, when a simple flushing of the pressure lines would not besufficient, the differential pressure bar must be cleaned with a cloth or a brush. The differentialpressure bar must first be disconnected from the transducer and removed from the duct/stack. Themaintenance intervals need to be shorter under such extreme application conditions.6. Make a zero point adjustment of the differential pressure transducer.The two wires on the transducer are cross-wired via the switching valve, and the exhaust screwsare opened briefly and shut again (pressure equalization at transducer).Remove the housing cover from the transducer to monitor the electric current signal on the display.The current output must now be 4.00 mA. If it is not, a zero point adjustment must be made.Remove both screws from the protective cover and remove the cover. Use the M key to proceed topoint 7 and perform the adjustment. Press and simultaneously for about 2 seconds. Thedisplay should now show 4.00 mA; if it does not, repeat the adjustment.7. Switch on the D-FL 100-10 Display.Use the MOD key on the D-FL 100-10 Display to proceed with the measuring process.GmbH