SECHRIST 3500HL (01) PDF Document

2.1 Using a 9/64″ allen wrench, attach the Proportioning Module to the calibrated Pressure Balancing Module with 4 screws. Ensure O-rings are in place.

2.2 Install the faceplate with 2 screws.

2.3 Install Assembly Tool 4 (bypass plate) to occlude high pressure inlet ports to the Alarm Module.

2.4 Using needle nose pliers, remove the bypass nipple.

2.5 Using a 1/4″ nut driver, install the brass plug into the bypass nipple port.

2.6 Install a flowmeter.

2.7 Connect Medical Breathing Air and Medical O2 supplies to the respective inlet adapters.

2.8 Connect the proportioning output to a calibrated O2 analyzer.

2.9 Select a flow of 7 LPM (Low Flow) or 15 LPM (Hi/Lo Flow) to the O2 analyzer.

2.10 Turn the adjustment shaft by hand until the O2 analyzer reads 30%.

2.11 Attach the Mixer knob to the adjustment shaft. Align the black indicator on the knob with the .30 position on the faceplate. Tighten the set screw just enough to attach the knob.

2.12 Turn the knob to the .90 position and check the O2 analyzer reading.

2.13 Using AT. 3, loosen the jam nut. Using AT. 2, adjust the rear seat until the O2 analyzer agrees with the knob reading of .90 ± 1%.

2.14 Turn the knob to the .21 position (making sure it hits the stop pin), then up to the .30 position. The O2 analyzer should read 30 ± 1%. If necessary, rotate the knob until a reading of 30 ± 1% is obtained, and reposition the knob to align the indicator with the .30 position.

2.15 Turn the knob to the .90 position; adjust the rear seat until the O2 analyzer reads 90 ± 1%.

2.16 Repeat steps 2.14 and 2.15 until proper readings are recorded.

2.17 Turn the knob to the 1.0 position; make sure the O2 analyzer reads at least 98% (no higher than 99.5%) and the knob is hitting the stop pin.

2.18 Using AT. 3, tighten the jam nut to secure the calibration of the rear seat.

2.19 Verify that the full range of positions can be obtained within a ±3% variation.

2.20 When calibrations are complete, tighten the knob set screw(s).

2.21 Turn gas supplies “OFF”, remove the bypass plate (AT. 4), and install the bypass nipple.

2.22 Calibration is now complete.

3.1 Slide the Alarm Module onto the bypass nipple and secure it to the Pressure Balancing Module with 2 screws. Ensure O-rings are in place.

3.2 With the Mixer still attached to gas supply lines, calibration can be performed.

3.3 Test for alarm bleed response: turn the O2 valve “ON” to 60 p.s.i., leave air “OFF”. The alarm should sound. Turn O2 down to 30 p.s.i.; the alarm should still sound. If it sounds throughout the 30-60 p.s.i. range, the alarm bleed is functional.

3.4 If the alarm isn’t functioning properly, check the reed before calibrating the alarm bleed.

3.5 To calibrate the bypass alarm O2 adjuster, turn O2 and air to “ON”, regulating to 50 p.s.i. The alarm should be silent.

3.6 Using gas regulators, set the air supply to 50 p.s.i. and slowly reduce the O2 supply. The alarm should sound between 24 p.s.i. and 28 p.s.i.

3.7 If no alarm sounds, loosen the jam nut, turn the O2 adjuster (located under the air inlet) counterclockwise slowly until the alarm sounds.

3.8 If the alarm sounds when the gas supply is turned on, turn the O2 adjuster clockwise until it stops, then counterclockwise just until it sounds.

3.9 Reduce O2 pressure to 0 and relieve pressure from the hose. After venting, no pressure should build in the O2 regulator gauge.

3.10 Open O2 pressure to 50 p.s.i.; the alarm should stop sounding at or before 40 p.s.i.

3.11 Tighten the jam nut over the O2 calibration adjuster to secure calibration.

3.12 To calibrate the bypass alarm air calibration adjuster, complete the steps above, replacing air for O2 in the instructions, and remembering the air adjuster is located under the O2 inlet.

General Disassembly Procedures

Before servicing, ensure all exterior connections are disconnected.

Disassembly into 3 Major Modules

4.1 To remove the Alarm Module, use a 7/64″ allen wrench to remove 2 screws.

4.2 Slide the Alarm Module straight back to clear the bypass nipple and lift it off the Mixer.

4.3 Remove the 2 screws from the faceplate and remove the faceplate from the Mixer.

4.4 Using a 9/64″ allen wrench, remove 4 screws from the Proportioning Module and separate it from the Pressure Balancing Module, being careful not to displace O-rings.

Proportioning Module Disassembly

1.1 Using a 1/16″ or 5/64″ allen wrench, release the knob by removing the set screw(s) and pull it off.

1.2 Use AT. 2 to insert into the front seat. Use a 1/2″ open end wrench to turn the spanner wrench and remove the front seat.

1.3 With the front seat removed, the double tapered needle will fall out.

1.4 Turn the module over to the rear seat.

1.5 Insert AT. 3 into the rear seat locking nut and loosen it using a 3/4″ open end wrench.

1.6 With the locking nut loosened, insert AT. 2 into the rear seat. Unscrew and remove the rear seat.

Pressure Balancing Module Disassembly

1.1 Ensure the Proportioning Module, Alarm Module, and faceplate are removed.

1.2 Using a 3/16″ allen wrench, remove 4 screws from the air block.

1.3 The module separates into 3 sections: air block, oxygen block, and diaphragm assembly.

1.4 Using tru-arc pliers, remove the tru-arc ring.

1.5 The cover disc will pop up, and the spring and regulator needle can be removed.

1.6 Using a 5/64″ allen wrench, loosen the set screw from the side of the block.

1.7 Using AT. 1, remove the eccentric adjuster.

1.8 The regulator seat can now be removed from either end.

Alarm Module Disassembly

1.1 Using tru-arc pliers, remove the tru-arc ring.

1.2 Remove the reed cap with the reed and reed retaining ring. Do not disassemble the reed cap assembly.

1.3 Using AT. 2, loosen the outside jam nut. Using AT. 1, remove the adjusters.

1.4 Using AT. 2, remove the adjustment cap cover.

1.5 Remove the spring.

1.6 Carefully remove the poppet.

1.7 The poppet and block can now be serviced.

1.8 Using AT. 1, remove the check valve retainer.

1.9 Remove the spring from the check valve retainer bore.

1.10 Remove the ball from the check valve retainer bore by forcing high pressure air through one of the poppet bores. CAUTION: DO NOT ATTEMPT TO DIG BALL OUT OF HOLE.

General Reassembly Procedure

With all modules serviced and calibrated, reassembly can be completed in the reverse order of the disassembly procedure.

Proportioning Module Reassembly

2.1 Before reassembling, inspect all O-rings and replace if cut, flat, or worn. Apply a light coating of Krytox to the front and rear seat O-rings.

2.2 Using AT. 2, install the front seat into the front seat port (identified by two stop pins), making sure not to tear the O-ring. Do not install the knob yet.

2.3 Turn the adjustment shaft counter-clockwise until resistance is felt.

2.4 Place the Proportioning Module front seat down, ensuring it is level.

2.5 Drop the double tapered needle into the rear seat port, making sure it stands up straight in the center.

2.6 Install the rear seat, working it carefully so the needle stays centered. Using AT. 2 (hand tighten only), screw the rear seat down (about 6 turns) past the first resistance until contact is made with the needle. Then, back off 1/2 turn.

2.7 Calibrate the Proportioning Module.

Pressure Balancing Module Reassembly

2.1 Inspect all O-rings and replace if necessary. Apply a light coating of Krytox to the regulator seat O-rings.

2.2 Place the regulator seat in the regulator seat port, centering it, with the small opening towards the inside of the block.

2.3 Install the eccentric adjuster, making sure it is flush with the block. If not flush, rotate with AT. 1 until it drops into place.

2.4 Install the regulator needle, spring, cover disc, and tru-arc ring. Ensure the O-ring is in position.

2.5 Calibrate the regulator needle in both the air and oxygen blocks.

2.6 Center the diaphragm assembly into the oxygen block.

2.7 Install the calibrated air block over the diaphragm assembly.

2.8 Install 4 screws to the module (hand tighten).

2.9 Using a soft mallet, position the 2 blocks so they are flush where the Proportioning Module mounts.

2.10 Tighten the 4 screws in a cross pattern to evenly distribute pressure.

Alarm Module Reassembly

2.1 Inspect all O-rings and replace if necessary. Apply a light coating of Krytox to all O-rings.

2.2 Install the ball in the check valve retainer bore.

2.3 Drop the spring in the check valve retainer bore.

2.4 Using AT. 1, install the check valve retainer.

2.5 Insert poppets (small end first) into the poppet bores.

2.6 Install the spring into the center of the poppet.

2.7 Using AT. 2, replace the adjustment cap cover.

2.8 Using AT. 1, install the adjuster, turning until resistance is felt (about 3 turns), then back off 1/2 turn.

2.9 Using AT. 2, tighten the jam nut over the adjuster (hand tighten only).

2.10 Calibrate the module.

Routine maintenance of the Mixer is limited to periodic checking and changing of the inlet filters and general cleaning. Refer to the Test Procedure and Troubleshooting Guide to determine when replacement is needed.

1.0 Inlet Filters

1.1 Periodically replace the air water trap/inlet filter as needed.

1.2 Replace the internal sintered stainless steel filters as needed.

NOTE: It is recommended that internal filters be removed one at a time to ensure inlet assemblies are not interchanged.

2.0 Cleaning

2.1 Exterior surfaces of the Mixer can be cleaned with a mild soap solution or wiped with a liquid disinfectant solution. Do not use cleaning agents that contain abrasives.

CAUTION: DO NOT IMMERSE THE MIXER. DO NOT GAS OR STEAM STERILIZE; DAMAGE MAY RESULT.