Flow Rate of Steam Schedule 40 Pipe

Related Resources: fluid flow

Flow Rate of Steam Schedule 40 Pipe

HVAC Systems and Components
Fluids Engineering and Design

Flow Rate of Steam in Schedule 40 Pipe Tables

Many heating systems for large industrial buildings use high pressure steam (15 to 150 psig). These systems usually have unit heaters or large built-up fan units with blast heating coils. Temperatures are controlled by a modulating or throttling thermostatic valve or by face or bypass dampers controlled by the room air temperature, fan inlet, or fan outlet.

Pressure Drop Steam per 100 ft of Length
Nominal Pipe Size, in.	1/16 psi (1 oz/in²)		1/8 psi (2 oz/in²)		1/4 psi (4 oz/in²)		1/2 psi (8 oz/in²)
	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig
	3.5	12	3.5	12	3.5	12	3.5	12
3/4	9	11	14	16	20	24	29	35
1	17	21	26	31	37	46	54	66
1-1/4	36	45	53	66	78	96	111	138
1-1/2	56	70	84	100	120	147	174	210
2	108	134	162	194	234	285	336	410
2-1/2	174	215	258	310	378	460	540	660
3	318	380	465	550	660	810	960	1,160
3-1/2	462	550	670	800	990	1,218	1,410	1,700
4	640	800	950	1,160	1,410	1,690	1,980	2,400
5	1,200	1,430	1,680	2,100	2,440	3,000	3,570	4,250
6	1,920	2,300	2,820	3,350	3,960	4,850	5,700	6,800
8	3,900	4,800	5,570	7,000	8,100	10,000	11,400	14,300
10	7,200	8,800	10,200	12,600	15,000	18,200	21,000	26,000
12	11,400	13,700	16,500	19,500	23,400	28,400	33,000	40,000

Pressure Drop Steam per 100 ft of Length
Nominal Pipe Size, in.	3/4 psi (12 oz/in²)		1 psi		2 psi
	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig	Sat. Press. psig
	3.5	12	3.5	12	3.5	12
3/4	36	43	42	50	60	73
1	68	82	81	95	114	137
1-1/4	140	170	162	200	232	280
1-1/2	218	260	246	304	360	430
2	420	510	480	590	710	850
2-1/2	680	820	780	950	1,150	1,370
3	1,190	1,430	1,380	1,670	1,950	2,400
3-1/2	1,740	2,100	2,000	2,420	2,950	3,450
4	2,450	3,000	2,880	3,460	4,200	4,900
5	4,380	5,250	5,100	6,100	7,500	8,600
6	7,000	8,600	8,400	10,000	11,900	14,200
8	14,500	17,700	16,500	20,500	24,000	29,500
10	26,200	32,000	30,000	37,000	42,700	52,000
12	41,000	49,500	48,000	57,500	67,800	81,000

Notes:
1. Flow rate is in lb/h at initial saturation pressures of 3.5 and 12 psig. Flow is based on Moody friction factor, where the flow of condensate does not inhibit the flow of steam.
2. The flow rates at 3.5 psig cover saturated pressure from 1 to 6 psig, and the rates at 12 psig cover saturated pressure from 8 to 16 psig with an error not exceeding 8%.

References

ASHRAE Handbook of Fundamentals, 2021 Inch-Pound Edition