Sanhua RFKH04E-2.9-19A Thermostatic Expansion Valve – R134a, External Equalizer, 1/2" Flare Outlet, 2.9 USRT

Sanhua RFKH04E-2.9-19A is a thermostatic expansion valve (TXV) made for R134a refrigerants. It continuously adjusts the refrigerant flow entering the evaporator according to the superheat at the evaporator outlet.

Externally Equalized (E) Body: Correct Superheat on Evaporators with Pressure Drop

The letter E in the model name indicates the external equalizer connection. An internally equalized valve takes the pressure at the evaporator inlet as its reference; if there is a significant pressure drop across the evaporator, this reference becomes misleading and the valve opens less than necessary. An externally equalized valve, on the other hand, measures the actual pressure at the evaporator outlet via a 1/4" equalizer line and keeps the superheat correct.

On multi-circuit evaporators, in systems using a distributor and on long evaporators, an externally equalized valve is mandatory.

Technical Specifications (Official Sanhua Datasheet R2511)

• Model: Sanhua RFKH04E-2.9-19A | Sanhua part no: 10201040602
• Refrigerant: R134a
• Rated Capacity: 2.9 USRT (≈ 10.2 kW)
• Equalizer Type: External equalizer (external equalizer)
• Connections: inlet 3/8" flare (flare nut) · outlet 1/2" flare (flare nut) · equalizer line 1/4" flare
• Evaporating Temperature Range: −40 … +10 °C (Range N)
• MOP: None — this variant is manufactured without the MOP function (Tab. A)
• Max. Working Pressure (PS): 4.6 MPa (46 bar)
• Ambient Temperature: −35 … +55 °C | Medium Temperature: −40 … +70 °C
• Capillary Tube: 1.5 m, stainless steel capillary and sensing bulb
• Thermostatic Charge: Cross charge — stable superheat across the entire evaporating range
• ⚠️ Orifice NOT INCLUDED. Datasheet scope of delivery: valve body + bulb clamp. The capacity is determined by the orifice, which must be ordered separately (0X ~ 6, available on our website). Orifice capacities for R134a: 0X 0.69 · 0 1.2 · 1 2.1 · 2 2.7 · 3 4.4 · 4 6.5 · 5 8.6 · 6 10.3 kW — full table in the 2nd image
• Certificates: UL/CSA · PED declaration

• 🔧 Code breakdown: RFKH = thermostatic expansion valve · 04 = R134a · E = external equalizer · 2.9 = rated capacity (USRT) · 19A = variant/connection digits.
• ℹ️ The "A" suffix indicates the new generation. Sanhua has updated the RFKH series; in the current catalog all codes are published with the A suffix. These versions have replaced the old codes without A.
• 🔧 Mount the sensing bulb correctly: it is clamped to the suction line, on a horizontal run, at the 3 or 4 o'clock position with full contact to the tube, and covered with insulation. If it is mounted under the tube (6 o'clock), oil accumulation causes false readings.
• Connect the equalizer line to the evaporator outlet, immediately after the bulb; a blocked or unconnected line completely disrupts valve operation.
• Cool the valve body with a wet cloth while brazing and purge with nitrogen; excessive heat damages the internal seal and the orifice.
• ⚠️ Refrigerant compatibility: This valve is charged for R134a. It must not be used in an R404A or R448A/R449A system — the thermostatic charge is different and superheat control will be off.