Identifying Valves Used in Sigma Products (SB1001.01)

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“D” size refrigeration valves Until the summer of 2001 Sigma used modified “D” L–N 2 coolant valves for refrigeration service. These valves were labelled D2024-S15. If the label is still intact, that number is all you need to identify the valve – go to page 23. Body Stamp About the summer of 2001 the “D” valves were upgraded with larger wattage coils, larger internal orifices to permit more flow and higher pressures, and a new outlet port location. The new valves were labelled with a Sigma number in the range of 35205-209. If the label is still intact, that number is all you need to identify the valve – go to page 23. If your valve does not have a label on it, a new “D” size valve can be distinguished from an older valve by the wrench flats on the sides of the body, an ID stamp on the top of the valve body, and the outlet port on the bottom. The older valve does not have wrench flats, has no body stamping, and has the outlet on the opposite side from the inlet. To see the body stamping, you need to remove the coil from the valve so you can see the top of the valve body. “D” valve with body stamp and wrench flats, 35205–209. Wrench flat Image 1-6 Because of the change in flow and pressure performance, new valves may be substituted for old valves with some plumbing changes, but not the reverse. See SB1002 for Troubleshooting Cryogenic Valves used Sigma in Thermal Chambers, SB1004 for Troubleshooting Cryogenic Valves Used in Sigma Thermal Platforms, and SB1003 for Valve Disassembly and Assembly instructions. Body stamp (not visible in this picture) Outlet Wrench flats Image 1-7 #32505–209 body – newer “D” body with wrench flats and Inlet on side and Outlet on base, and body stamp. D2024-S15 body – older “D” body with Inlet on side and Outlet on opposing side. SB1001.01-4
Valves for cryogenically cooled systems Sigma Systems Liquid Nitrogen (L–N 2 ) and Liquid Carbon Dioxide (L–CO 2 ) cooled systems have nearly always used custom made valves that are peculiar to Sigma Systems. Sigma equipment built up to the early 1990’s used Sigma designed valves built by ASCO. In the mid 1990’s Sigma changed to an improved design that is custom built for Sigma. ASCO built Sigma valves are characterized by a small valve body with a machined grove around the bottom and a typically large green actuating coil housing. Newer design Sigma valves are typically smaller, have a stainless steel body and a black coil housing that is about the same diameter as the body (image 1-8). As of the writing of this bulletin, most parts for the ASCO valves were still available from Sigma. The ASCO valves typically have a label on the coil that identifies the valve. If you call Sigma for parts, it will be very helpful if you have the number. ASCO valve on the left and two newer custom designed Sigma valves. Image 1-8 The design changes that accompanied the move away from ASCO built valves resulted in valves that run quieter and far longer. The balance of this section deals with identifying these more modern valves. L–N 2 or L–CO 2 ? While Sigma L–N 2 valves look very similar to L–CO 2 valves (image 1-9), there are significant differences. If you are certain that you know which coolant (L–N 2 or L–CO 2 ) your system uses, proceed with this section. The rest of this section relies on your certainty. If you are not certain which coolant your system uses, go to page 15 to determine your valve type by analyzing it’s parts. L–N 2 valves On the surface L–N 2 and L–CO 2 valves look very similar, inside there are significant differences. Image 1-9 Sigma has used a variety of custom L–N 2 valves. Size is the first distinction you need to make. Image 1-10 shows the two sizes. The larger valve is a “D” size valve, it is roughly 1⁵⁄₈” (41mm) diameter and almost 3” (76mm) tall. The smaller valve is known as a “B” size valve, it is roughly 1¼” (32mm) in diameter and 2³⁄₈” (60mm) tall. For “D” size L–N 2 valves skip to page 11. “D” size valve “B” size valve For “B” size L–N 2 valves continue on page 6. Image 1-10 SB1001.01-5
Page 1 and 2: Service Bulletin #SB1001.01 Identif
Page 3: “B” size refrigeration valves U
Page 7 and 8: To identify the valve you must disa
Page 9 and 10: Check the plunger guide, the seal,
Page 11 and 12: “D” size L-N 2 valve identifica
Page 13 and 14: Beginning late summer 2001, new val
Page 15 and 16: Identifying Loose Valves and Parts
Page 17 and 18: Web “B” Size valves (con’t fr
Page 19 and 20: Gap Image 1-48 A Variseal seal in V
Page 21 and 22: Actuating Coils Valve actuating coi
Page 23 and 24: Identifying Valves by Valve Numbers
Page 25 and 26: 1. Removing the coil retention nut
Page 27 and 28: 4. Removing the plunger guide - Onc
Page 29 and 30: To Reassemble the valve. 1. Make su

Identifying Valves Used in Sigma Products (SB1001.01)

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