Pressure drop (ΔP) is the loss of static pressure as fluid moves through nozzles, headers, tubes, baffles, and exits. Pumps, compressors, and gravity systems are sized to a remaining available ΔP. If the exchanger consumes more than allowed, the plant cannot make rate.
Tube-side ΔP
Tube-side drop is dominated by straight-tube friction and return losses in the channel. More tube passes raise velocity and ΔP (and usually the heat-transfer coefficient). Diameter, length, roughness, and fittings matter. State allowable tube-side ΔP in bar or kPa — and whether it includes nozzles.
Shell-side ΔP
Shell-side drop is set by cross-flow over tubes, window flow at baffle cuts, and leakage streams (bundle-to-shell, tube-to-baffle). Closer baffles raise ΔP and can raise the film coefficient — until vibration or erosion limits are hit. J, G, H, and X shells exist specifically for low-ΔP services.
What happens if you leave ΔP blank
The designer must assume a value. That assumption may not match your pump curve. Always write allowable shell-side and tube-side pressure drop on the RFQ, including the design margin your process engineer wants.
RELATED EQUIPMENT FROM OHM ENGINEERS