Fantail VSP High Pressure Air System

Owned by jr_crowder
Last updated: Apr 18, 2019
4 min read

Installed 378P, replaces the GD31 regulator

Purpose

The high pressure air manifold delivers air to the seismic sources for vertical seismic profiling (VSP) experiments during downhole logging operations.   The manifold is designed so the user can deliver air pressure to the seismic source over a range from 0 to 2000 psi which is the upper limit of the air pressure delivered on the JR.  

Environmental Impact

The use of seismic (acoustic) sound sources on the JR is done in accordance to National Science Foundation/USGS guidelines and if in a country’s territorial waters, any regulations imposed by that country.  An Environmental Evaluation (EE) document is prepared for every expedition that has a proposal to perform seismic work to evaluate the impact to marine mammals and endangered species.  Consult the EE and the Lab Officer prior to performing any seismic work.

 

The general procedure includes a protected species observation protocol and a low to high pressure air (soft start) ramp up procedure.  Obtain instructions and permission from the LO prior to any seismic work.

Safety

WARNING – High Pressure Air in Use

  • The high pressure air manifold should be used by experienced personnel only.

  • Wear appropriate PPE.

  • All personnel stand inboard of the manifold when the main ship’s input air valve is turned on.

  • Never deliver more than 200 PSI to the G Guns while they are on the deck.

  • During pressure tests of the manifold or G Guns, keep all non-essential personnel away.

Components

Swagelok RDHN6-02-7-VVK-GN5 (includes RSN2-02-4-VVK-NV) DOME LOADED PRESSURE-REDUCTING REGULATOR, 0-2537 PSI, 3/4" FNPT.

This is a custom order from Baytown Valve and Fitting, see AMS 1710166JOM for details.

 

These diagrams show the parts of the manifold that are described in the operating procedures below.

Operation Procedure

Read these instructions and familiarize yourself with the parts of the system before operating.

  1. Ensure that the Price Air Compressors are on line (call the engine room to inquire about status - Ext 290 ECR).  Check that the main valve before the accumulator is open at least 45 degrees.  Check the pressure on the large gauge.

  2. Ensure the output isolation valve and dump line isolation valves are closed.

  3. Make sure the red pressure control valve is backed off, just enough to see the hole on the shaft, and open the bleed valve.

  4. Stand inboard of the manifold and turn the yellow handled switch valve on to get ship’s high-pressure air to the manifold.

  5. You should have approximately 1800 - 2000 PSI at the input air gauge (Gauge on the left).  Observe if there is any pressure on the output side (Gauge on the right). If so, you can bleed the air following the instructions below.**SEE BELOW**

  6. The red control knob is used to increase and decrease the output pressure.  Note the increase and decrease directions labeled on the end of the red knob. 

    1. To increase the pressure, slowly turn the knob clockwise to the desired output pressure (Gauge on the right).

    2. To decrease the pressure, make sure the adjustment bleed valve (black knob above the red knob) is still open and slowly turn the knob counterclockwise until you reach the desired pressure (Gauge on the right).  The adjustment bleed valve can be left open and always be bleeding a little air.  **Either the dump valve needs to be opened or the gun lines must be attached and the guns firing to lower the pressure. **

  7. Once at the desired output pressure, open the output isolation valve to send air to the air guns. 

    1. WARNING: Do not send more than 200 psi to the guns while on deck.

    2. Send 500 psi to the guns while they are hanging over the water and just prior to them entering the water to keep any salt water from getting inside the system.

  8. To adjust the output pressure from there, use the red control knob to increase the pressure and the control knob and adjustment bleed valve to decrease the pressure.

  9. When the seismic experiment is finished, lower the output pressure to 500 psi.  You may need to fire the guns one last time or open the dump isolation valve to lower the pressure.  You want to keep air pressure in the guns while they are in the water to prevent salt water from getting inside the guns and airlines. 

  10. Bleeding the output side - Once the guns are clear of the water but before they are swung down to the deck or you are finished with a pressure test, bleed the remaining air pressure from the output side by opening the dump line isolation valve, and adjusting the control knob to 0 psi output.

  11. Bleeding the input side – When finished with testing or the seismic experiment you will want to bleed pressure from the manifold.  Close the main input isolation valve.  Open the dump line isolation valve and increase on the red knob enough so that all of the pressure is bled off.  Leave the red knob backed off or decreased for the next user.

  12. Always leave the system with no pressure, close all of the valves, and cap any openings (the end of the bleed line can remain open).

**UPDATE 368X**

At the writing of this manual on 368X we notice the regulator behaving differently than it did after it was first installed and used for a test prior to 368X.  If all of the output valves are closed, the pressure on the output gauge will rise to full pressure.  If you see this behavior, open the dump valve a little before opening the isolation valve, this way high pressure is not sent down the lines.  With the dump valve open the pressure will bleed off quickly and you can regulate from there.   With the airline to the guns attached, be careful that the pressure can also rise on that side when the guns are not firing.