Description
Restriction unions are used in piping systems for sizes typically less than 2” where the use of flanges is prohibitive or unavailable and are used to restrict pressure or flow. AVCO supplies these unions for female NPT, male NPT, socket weld, compression and AN fitting connections. Female restriction unions (NPT & socket weld) have replaceable orifice plates which can be used for pressure restriction in gas or liquid systems. For choked flow, it is often overlooked that standard restriction unions are not sufficient. AVCO has in-depth knowledge of flow restriction and has developed many different styles to ensure flow is properly restricted. For gases, the throat length must be between 1 and 6 times the orifice bore for critical/choked flow to occur. In liquids choked flow will occur across a standard plate, but cavitation due to the high pressure drop and resultant temporary drop below the liquid vapor pressure, will cause noise and possible damage to the upstream piping. To alleviate this the throat length should be in the region of 6 times the orifice bore thus containing the cavitation zone and eliminating the requirement for frequent replacement. AVCO offers several specialized restriction unions to enable greater throat lengths in both tubing and piping systems to give reliable protection of your critical equipment.
