mech17.txt
mech17.txt — 1.5 KB
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Office of Air Quality, New Source Review Program Mechanical Section Policy Memorandum Date: December 20, 1994 No.: 17 From: Skip Clark, P.E. Approved by: Gary Wallin, P.E. Subject: Standard Exemption No. 24 Policy: The intent of Standard Exemption No. 24 was to cover sand or investment molds from the time they are made until they are broken apart. No other equipment, or processing was intended for this exemption. Also, the size of the castings is limited to 100 pounds or less per casting. Background: Historically, molds for castings that are less than 100 pounds per casting do not tend to emit large amounts of particulate matter or other pollutants while they are being formed and/or used. The 100 pound per casting is defined as the actual weight of the casted part, irregardless of how much is actually melted to cast that part. If the company wants to melt 125 pounds of metal to make sure of enough melt to fill the mold, the excess is not counted toward the weight of the casting. The potential to emit air containments is mainly concentrated in the furnace area and the break-out and sand reclamation systems. Larger mold making equipment can be covered under Standard Exemptions Nos. 23 or 44. The melting and holding furnaces that are used in these processes may be covered under Standard Exemption Nos. 7, 17, 58 or 96. Necessary Action: None cc: All Mechanical Section