118 Maintenance Caution 1. Installation and removal of tubing for One-touch fittings 1) Installation of tubing (1) Cut the tubing perpendicularly, being careful not to damage the outside surface. Use an SMC tube cutter “TK-1”, “TK-2” or “TK- 3”. Do not cut the tubing with pliers, nippers, scissors, etc., otherwise, the tubing will be deformed and trouble may result. (2) The outside diameter of the polyurethane tubing swells when internal pressure is applied to it. Therefore, it may be possible that the tubing cannot be re-inserted into the Onetouch fitting. Check the tubing outside diameter, and when the accuracy of the outside diameter is +0.07 mm or larger for o2, +0.15 mm or larger for other sizes, insert into the Onetouch fitting again, without cutting the tubing to use it. When the tubing is re-inserted into the One-touch fitting, confirm that the tubing goes through the release button smoothly. (3) Grasp the tubing, slowly push it straight (0 to 5°) into the One-touch fitting until it comes to a stop. (4) Pull the tubing back gently to make sure it has a positive seal. Insufficient installation may cause air to leak or the tubing to release. 2) Removal of tubing (1) Push the release button flange evenly and sufficiently to release the tube. (2) Pull out the tubing while keeping the release button depressed. If the release button is not held down sufficiently, the tubing cannot be withdrawn. (3) To reuse the tubing, remove the previously lodged portion of the tubing. If the lodged portion is left on without being removed, it may result in air leakage and removal of the tubing difficult. 2. Connecting products with metal rods Products with metal rods (Series KC, old Series KQ, Series KN, and Series KM, etc.) cannot be connected to Series KQ2 One-touch fittings. If connected, the metal rod cannot be retained by the chuck of the One-touch fitting and products with metal rods may project during pressurization, causing serious personal injury or accident. Even when products with metal rods can be connected to other One-touch fittings, do not use any tube, resin plug, or reducer after connection. This may cause releasing. For details about One-touch fittings that can connect products with metal rods, contact SMC. Caution 1. Be certain to wear safety glasses at all times during periodical inspections. 2. Replace fittings or tubing having the following problems. 1) Cracks, gouges, wearing, corrosion 2) Air leakage 3) Twists or crushing of tubing 4) Hardening, deterioration, softening of tubing 3. When replacing tubes or fittings, do not try to mend or repair and then reuse them. Connection Thread Tightening Method 1. Connection thread: M3 First, tighten by hand, then use a wrench appropriate for the hexagon flats of the body to tighten an additional 1/4 turn. A reference value for the tightening torque is 0.4 to 0.5 N・m. 2. Connection thread: M5 and 10-32UNF First, tighten by hand, then use a wrench appropriate for the hexagon flats of the body to tighten an additional 1/6 to 1/4 turn. A reference value for the tightening torque is 1 to 1.5 N・m. 3. M6 First, tighten by hand, then use a wrench appropriate for the hexagon flats of the body to tighten an additional 1/6 to 1/4 turn. Note) Excessive tightening may damage the thread portion or deform the gasket and cause air leakage. Insufficient tightening may loosen the threads, or cause air leakage. 4. Fittings with sealant: R, NPT 1. First, tighten the fitting by hand, then use a wrench appropriate for the hexagon flats of the body to tighten it a further two or three turns. For a tightening torque guide, see the table below. 2. If the fitting is tightened with excessive torque, a large amount of sealant will seep out. Remove the excess sealant. 3. Insufficient tightening may cause seal failure, or loosen the threads. 4. Reuse 1) Normally, fittings with a sealant can be reused 2 to 3 times. 2) To prevent air leakage through the sealant, remove any loose sealant stuck to the fitting by blowing air over the threaded portion. 3) If the sealant no longer provides effective sealing, wrap sealing tape over the sealant before reusing. Do not use the sealant in any form other than a tape type. 4) Once the fitting has been tightened, backing it out to its original position often causes the sealant to become defective. Air leakage will occur. One-touch Fittings Mounting/Piping Caution 3. When mounting tubes, resin plugs, reducers etc., do not press the release button. Also, do not press the release button before mounting. This may result in detachment. In particular, when piping products, such as plug-in elbows or reducers, etc. the release button may be pressed easily due to product handling during piping work. One-touch Fittings Mounting/Piping Fittings & Tubing Precautions 3 Be sure to read this before handling. Connection thread size (R, NPT) Tightening torque (N・m) 1/16, 1/8 3 to 5 1/4 8 to 12 3/8 15 to 20 1/2 20 to 25 A