Shear Pin Piston Test

Conducted by: Jenna Blair (815-871-7868), Claire Johnson

Location: Blast Chamber

Date: 12/3/23

Time: 1400-1700

 

Safety Precautions:

  • All participants must wear safety glasses.

  • Range safety officer must audibly countdown before the test and ensure that everyone is paying attention.

  • Test articles should not fragment into sharp, hard pieces during the test sequence.  This is ensured by eliminating any unfastened materials within the body sections, and limiting the amount of pyrotechnic charge used.

  • The SO should inspect all test articles prior to initiating the piston test.

  • Appropriate PPE will be used when installing the charge prior to the test (i.e. safety goggles and nitrile gloves). There will never be skin contact with the charge

  • If a misfire occurs:  wait at least 60 seconds and disconnect the battery (or use an alternative method to disable the testing mechanism) before allowing anyone to approach the test article.

  • Strict 25 foot keep-out zone must be established, which all test participants must obey. Members should ensure that no bystanders are present. The SO must ensure that no one is in the expected path of the projectile regardless of distance from the test articles. Mark of the test area (such as with caution tape) or otherwise guard entrances from bystanders.

  • All debris must be cleared out of the blast chamber when the test is complete.

  • Call MIT Police 617-253-1212 to report an emergency. 

  • Email Anthony Zolnik about blast chamber usage and receive approval or confirmation. 

    NOTE: Because there is no smoke or venting of fumes, members and the SO do not need to contact police before testing; however, it is required we reach out to at least one facilities manager (Anthony). 

Goals:

  • Evaluate the performance of two new designs for black powder capsules

Materials:

Tools:

  • 2 adjustable crescent wrenches

  • Gloves

  • Alligator clips

  • Bricks/sandbags/weights

  • Safety glasses 

  • Close toed shoes

  • A very long wire

  • Multimeter

  • 9V battery

  • Scale

  • Teflon tape

Hardware:

  • 2 pistons

  • 4 Brass NPT Plugs with one hole

  • 8n Brass NPT Reducing Adapters
  • 8 Burst Disk Washers
  • 4x 6-32 shear pins (per piston)

  • 4 1/4-20 screws

Consumables:

  • Black powder (0.1g for one capsule, 0.15 g per capsule for two capsule, 0.2 for one capsule)

  • 16 e-matches

Procedures:

Check-offs:

  • Fit check

  • Reserve the blast chamber

Piston Integration Procedures: 

  • Using a 1/4 inch torque wrench, ensure that the bolts holding the piston together are tight (100 inch-pounds of torque). If the bolts are loose, the piston will lose pressure as it extends. (torque wrench adapter in piston box)

  • Screw piston mount and diaphragm (upside down from phoenix orientation) onto piston
  • Ensure piston rod is completely compressed
  • Put set screws into diaphragm
  • Put shear pins into piston mount

  • Use multimeter to check continuity of E-match (should be about 1.0-1.4 ohms) and twist the wires to short it. Two people should visually confirm that it is shorted. 

  • Integrate Black Powder into NPT Plug

  • Wrap the NPT Plug with five wraps of Teflon tape. 

  • Wrap Burst Disk Washer with Teflon tape and press it into the NPT Reducing Adapter

  • Use the 7/16 wrench to screw Black Powder Capsule into the NPT Reducing Adapter as far as possible

  • Repeat steps a through c for a second Black Powder Capsule

  • Everyone put on safety glasses. From now on, everyone within the vicinity of the pyrotechnics must wear safety glasses.

  • Compress the piston completely!

  • Screw the entire fitting assembly into the piston NPT hole. Make sure that the fitting assembly is pointed up (in the direction of the bore) and rotate Black Powder Capsule until the side plug is as close to the body of the piston as possible.

  • Test the piston by pulling up rod for 5 secs and checking that it is sealed

  • Log Firebolts

Black Powder Capsule Testing Procedures:

  • Perform integration according to the Piston Integration Procedures above.

  • Run wires from outside to inside the blast chamber. Make sure that the wires are shorted on the outside of the blast chamber. On the inside, unshort the e-match leads and connect it to the wires.

  • Place the piston in the vacuum chamber (firebolt-fitting assembly pointing down).

  • Clamp the piston between two bricks. 

  • Put the lid on the chamber and turn on the vacuum pump until pressure level reaches 0 psi. 

  • Only after exiting the chamber and closing the door, perform a countdown and connect the outside wires to a voltage source (battery).

  • In the event of a misfire, disconnect the battery and wait at least 60 seconds before allowing anyone to enter the chamber/approach the test article.

  • After firing, wait at least 60 seconds before entering the blast chamber.

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