Natural Gas Ejectors Frequently Asked Questions

Ten Most Commonly Asked Questions about Fox Natural Gas Ejectors

1. How much high pressure gas does it use?

Fox will be happy to run your specific application through our proprietary computer model and supply technical data promptly. There are no easy rules of thumb. Please complete our standard application Data Sheet, and be sure to indicate if turndown is required.

2. Does staging multiple ejectors reduce the amount of gas we need to use?

No. This works with steam—a condensible—but not with hydrocarbons. Request our bulletin on Vapor Recovery Ejectors for a more detailed explanation.

3. We want to install one ejector and vary/reduce/conserve the motive gas flow rate as the suction/leakage gas flow rate varies. Will that work?

Usually not. Ejectors in most gas capture/vapor recovery applications have a high compression ratio and therefore are very sensitive to changes in motive gas flow rate. High compression ejectors can be considered to have no turndown. Multiple ejectors installed in parallel, with on/off valves, is an option to compress a widely varying range of gas flow rates.

4. We have multiple sources of methane leakage and emissions. Do I need a separate ejector for each source?

No. A gathering manifold can collect leakage from multiple sources, and be connected to the suction of one ejector.

5. Can ejectors be noisy? What can Fox do to reduce noise?

Although not as noisy as steam ejectors, vapor recovery ejectors can be loud. When noise abatement is required, we typically enclose the ejector within a sealed jacket that contains acoustical insulation.

6. What is a typical delivery? Are they stock items?

Two types of ejectors fall in this category:

Ejectors that are used to simply vent or capture emissions from tanks, vessels, etc., and discharge to a flare header or another low pressure destination can make use of Fox’s large inventory of stock air ejector components (1/2″ to 3″), which can be very quickly modified to suit gas temps, composition and pressures, welded with flanges, hydrotested and shipped in less than a week.

Ejectors that accomplish significant compression are custom designed:

If 4″ line size or smaller, typical delivery is 5 – 6 weeks, but expediting is possible to shipment in a week (depending on QA requirements).

6″ – 18 ” line sizes. Typical delivery is 8 – 10 weeks, but expediting is possible

7. What else can Fox supply with the ejector?

Fox has been supplying skid mounted ejector systems for decades. Tell us what you need.

8. Are ejectors used to compress methane or natural gas a recent invention?

Certainly not. Please request a copy of a 1954 article in ‘Petroleum Refiner’ describing a number of ejector installations.