Liquid cooling
CPC Everis LQ4 vs LQ6: Tube Size and Flow
Use LQ4 for 1/4 inch to 3/8 inch tube. Use LQ6 for 3/8 inch to 1/2 inch tube. Both publish vacuum to 120 psi and 0°F to 240°F.
On this page
Use Everis LQ4 when the tube is 1/4 inch to 3/8 inch inside diameter (6.4 mm to 9.5 mm) and the coupling is the 1/4 inch flow series. Use Everis LQ6 when the tube is 3/8 inch to 1/2 inch inside diameter (9.5 mm to 12.7 mm) and the coupling is the 3/8 inch flow series. Both product pages and both 2026 spec sheets, as of October 21, 2026, list vacuum to 120 psi (8.3 bar) and an operating range of 0°F to 240°F (-17°C to 115°C). The LQ4 product page and the LQ4 sheet both list a maximum flow at disconnect of 3.0 gal/min (11.3 L/min). The sheets list a flow coefficient of about 1.4 Cv (1.2 Kv) for LQ4 and about 2.2 Cv (1.9 Kv) for LQ6.
Tube size is the split
The LQ4 product page, as of October 21, 2026, describes quick disconnects with 1/4 inch flow. Tubing sizes are 1/4 inch to 3/8 inch ID, 6.4 mm to 9.5 mm ID. The listing count on that page was 44 of 44. Terminations visible there include 1/4 inch and 3/8 inch NPT, 1/4 inch ID by 3/8 inch OD PTF, 1/4 inch and 3/8 inch hose barb, locking hose barb, SAE thread, and G-thread/BSPP, in Cool Blue and Warm Red, as valved in-line bodies.
The LQ6 product page, as of October 21, 2026, describes 3/8 inch flow. Tubing sizes are 3/8 inch to 1/2 inch ID, 9.5 mm to 12.7 mm ID. The listing count was 40 of 40. Terminations visible there include 3/8 inch and 1/2 inch NPT, 3/8 inch ID by 1/2 inch OD PTF, 3/8 inch and 1/2 inch hose barb, locking hose barb, SAE thread, and G-thread/BSPP, again in Cool Blue and Warm Red. A 1/4 inch hose barb is an LQ4 termination on that page. A 1/2 inch hose barb is an LQ6 termination. The pressure and temperature windows compare LQ6 with UQD specifications. They do not choose LQ4 or LQ6 from the tube.
Pressure, temperature, and housing
On both product pages the pressure line is vacuum to 120 psi, 8.3 bar, and the temperature line is 0°F to 240°F (-17°C to 115°C). The 2026 spec sheets print the same pressure and the same operating line. Main housing components are plated brass on the product pages and on the sheets. Lubricant is Krytox PFPE on both. The product pages list the valve spring and the external spring as stainless steel. The LQ6 product page names 302 stainless steel for those springs. The sheets say stainless steel. Seal rows on the product-page materials tables say EPDM. The product-page seal filter also lists EPDM.
Both 2026 sheets say seals are EPDM standard, with FKM and FVMQ options. Plated brass, the EPDM materials row, and stainless springs appear on the product page and on the sheet. The seal suffix that changes the low operating temperature is on the FVMQ note.
Cv on the sheets, and the LQ4 disconnect flow
The 2026 LQ4 sheet lists flow coefficient Cv about 1.4 (1.2 Kv). The 2026 LQ6 sheet lists Cv about 2.2 (1.9 Kv). The product pages opened October 21, 2026 have a specifications heading that mentions Cv and do not print those coefficients. Use the sheet for the Cv, and name the sheet's copyright year, 2026, on the request.
Maximum flow at disconnect for LQ4 is 3.0 gal/min, 11.3 L/min, on the product page and on the 2026 sheet. The sheet adds that this disconnect flow is at 0 to 120 psi. LQ4 spillage on the product page is less than 0.025 cc per disconnect at 0 psi and less than 0.055 cc per disconnect at 120 psi. LQ4 air inclusion on the product page is less than 0.25 cc per connect. LQ6 spillage on the product page is less than 0.03 cc per disconnect at 0 psi and less than 0.03 cc per disconnect at 120 psi.
| Series | Nominal flow | Tube inside diameter | Pressure | Operating temperature | Cv on the 2026 sheet |
|---|---|---|---|---|---|
| LQ4 | 1/4 inch | 1/4 in to 3/8 in (6.4 mm to 9.5 mm) | Vacuum to 120 psi, 8.3 bar | 0°F to 240°F (-17°C to 115°C) | about 1.4 (1.2 Kv) |
| LQ6 | 3/8 inch | 3/8 in to 1/2 in (9.5 mm to 12.7 mm) | Vacuum to 120 psi, 8.3 bar | 0°F to 240°F (-17°C to 115°C) | about 2.2 (1.9 Kv) |
Part numbers the LQ4 sheet prints cleanly
The 2026 LQ4 sheet's termination table includes in-line 1/4 inch NPT as LQ4D24004RED and LQ4D24004BLU, and 3/8 inch NPT as LQ4D24006RED and LQ4D24006BLU. In-line PTF at 1/4 inch ID by 3/8 inch OD is LQ4D20006RED and LQ4D20006BLU. A footnote says SAE terminations are compatible with SAE J1926-1 ports, and G (BSPP) terminations are compatible with ISO 1179-1 ports. RED and BLU are the Warm Red and Cool Blue bodies. The hose-barb rows a buyer needs are on the product-page list. Copy the full part number from the row that matches the port on the drawing.
CPC prints a warning on the product pages and on the sheets: pressure, temperature, chemicals, and the operating environment can affect the coupling, and the customer tests suitability in the application. The series choice above is the tube and the nominal flow. It is not a loop calculation.
What to name on the coupling request
- Series: LQ4 or LQ6, from the tube inside diameter.
- Termination and the part number, including Cool Blue or Warm Red.
- Vacuum to 120 psi, 8.3 bar, if that is the pressure the design uses.
- 0°F to 240°F, unless the seal suffix on the FVMQ sheet changes the low end.
- Fluid. The pages list seal options for glycol/water or dielectric coolants and do not assign one seal to one fluid.
- Cv from the 2026 sheet if the request asks for a flow coefficient: about 1.4 for LQ4, about 2.2 for LQ6.
Questions these four documents answer
Does the larger series raise the pressure rating?
LQ4 and LQ6 both print vacuum to 120 psi, 8.3 bar, on the product page and on the 2026 sheet. The larger series changes the tube size, the nominal flow name, and the sheet Cv.
Which series takes a 3/8 inch tube?
LQ4's tubing line ends at 3/8 inch ID. LQ6's tubing line starts at 3/8 inch ID. A 3/8 inch tube sits on both lines. The nominal flow name is still 1/4 inch for LQ4 and 3/8 inch for LQ6. Pick the series the manifold port already uses, and copy that part number.
Does the body color choose the seal?
Cool Blue and Warm Red are the colors on the product list. The materials table still says EPDM. The 2026 sheets say to add V for FKM and FLS for FVMQ. Color and seal suffix are separate marks on those sheets.
Sources
Tube sizes, pressure, operating temperature, housing, springs, EPDM, spillage, and the LQ4 disconnect flow are from the CPC product pages, checked against the 2026 spec sheets where both documents print the figure. Cv values and the SAE and BSPP port notes are from the spec sheets. Pages and sheets were opened October 21, 2026.