Introduction

Sample streams discharged from process analyzers have historically been vented to atmosphere for disposal. This method is not only convenient, but also provides a very stable reference pressure necessary to insure accurate and repeatable analysis results. As environmental legislation becomes more stringent, sample discharge to atmosphere is no longer allowable in many cases and analyzer engineers must choose an alternate method. Catalytic burners offer one alternative, however they do not completely eliminate emissions, have a limited flow capacity and require frequent maintenance. Discharge to a vent header that subsequently feeds a flare header and stack offers another choice, but the dynamic nature of the header is not conducive to pressure stability which compromises analysis accuracy. Complex vent systems installed plant-wide are also available, but they are highly engineered and expensive to install.

The Parker Vent Master is a totally mechanical integrated solution that actually creates a stable pressure within the vent header within 0.3" H20. Test results prove the Vent Master provides analysis accuracy within 0.06% over a vent header flow range of 0-18 SLPM with a flare header back pressure as high as 20 psig.

The Vent Master is comprised of regulators, gauges, a rotometer and an eductor assembled in a compact panel for ease of operation and installation. A separate Pressure Controller is mounted directly to the vent header providing a constant flow of N2 to the header at a rate sufficient to maintain a constant pressure of approximately 1" H20. As multiple analyzers dispose sample gas into the header by varying amounts, the Vent Master senses the header pressure and compensates to maintain a constant pressure regardless of discharge volume. The Vent Master also isolates the vent header from Flare Header pressure fluctuations up to 20 psig with test results indicating stability within 0.3" H2O.