Control Valve Pressure Related Chart float valves for water tanks

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A control valve has two main parts: an actuator and a valve. The actuator controls the movement of the valve stem, while the pilot valve senses the pressure inside the pipe and opens and closes the valve accordingly.

In order to maintain constant pressure throughout the entire piping system, a control valve should be installed on each processing system.

Control Valves 101: Valve Types, Applications, Components, and Accessories

The control valves regulate the flow of water through pipes by opening and closing in response to changes in pressure. The valves also allow for adjustments to the amount of water flowing through the pipe.

What are the different types of control valves in industries?

Control Valve Pressure-Temperature Chart

Pressure control valves are used in a wide range of applications where accurate control of fluid pressures is required. They are often used in situations where a constant flow rate, pressure, or temperature is desired. In these cases, the flow rate can be controlled by a valve with constant opening size. This type of valve is commonly known as a “pressure control valve”. Different temperatures bear different pressure ratings for control valves, the following chart is the pressure-temperature relationship of control valves.

Control Valve Pressure-Temperature Chart for Standard Class ASTM A216 Grade WCC Cast Steel In Accordance with ASME B16.34-2013

Temperature	Class 150	Class 300	Class 600	Class 900	Class 1500
°C	Bar
-29 to 38	19.8	51.7	103.4	155.1	258.6
50	19.5	51.7	103.4	155.1	258.6
100	17.7	51.5	103.0	154.6	257.6
150	15.8	50.2	100.3	150.5	250.8
200	13.8	48.6	97.2	145.8	243.2
250	12.1	46.3	92.7	139.0	231.8
325	9.3	41.4	82.6	124.0	206.6
350	8.4	40.0	80.0	120.1	200.1
375	7.4	37.8	75.7	113.5	189.2
400	6.5	34.7	69.4	104.2	173.6
425	5.5	28.8	57.5	86.3	143.8
°F	psig
-20 to 100	290	750	1,500	2,250	3,750
200	260	750	1,500	2,250	3,750
300	230	730	1,455	2,185	3,640
400	200	705	1,405	2,110	3,520
500	170	665	1,330	1,995	3,325
600	140	605	1,210	1,815	3,025
650	125	590	1,175	1,765	2,940
700	110	555	1,110	1,665	2,775
750	95	505	1,015	1,520	2,535
800	80	410	825	1,235	2,055

Control Valve Pressure-Temperature Chart for Standard Class ASTM A217 Grade WC9 Cast Steel In Accordance with ASME B16.34-2013

Temperature	Class 150	Class 300	Class 600	Class 900	Class 1500
°C	Bar
-29 to 38	19.8	51.7	103.4	155.1	258.6
50	19.5	51.7	103.4	155.1	258.6
100	17.7	51.5	103.0	154.6	257.6
150	15.8	50.3	100.3	150.6	250.8
200	13.8	48.6	97.2	145.8	243.4
250	12.1	46.3	92.7	139.0	321.8
300	10.2	42.9	85.7	128.6	214.4
325	9.3	41.4	82.6	124.0	206.6
350	8.4	40.3	80.4	120.7	201.1
375	7.4	38.9	77.6	116.5	194.1
400	6.5	36.5	73.3	109.8	183.1
425	5.5	35.2	70.0	105.1	175.1
450	4.6	33.7	67.7	101.4	169.0
475	3.7	31.7	63.4	95.1	158.2
500	2.8	28.2	56.5	84.7	140.9
538	1.4	18.4	36.9	55.3	92.2
°F	psig
-20 to 100	290	750	1,500	2,250	3,750
200	260	750	1,500	2,250	3,750
300	230	730	1,455	2,185	3,640
400	200	705	1,410	2,115	3,530
500	170	665	1,330	1,995	3,325
600	140	605	1,210	1,815	3,025
650	125	590	1,175	1,765	2,940
700	110	570	1,135	1,705	2,840
750	95	530	1,065	1,595	2,660
800	80	510	1,015	1,525	2,540
850	65	485	975	1,460	2,435
900	50	450	900	1,350	2,245
950	35	385	755	1,160	1,930
1000	20	265	535	800	1,335
1050	20(1)	175	350	525	875
1100	20(1)	110	220	330	550

Flanged end ratings terminate at 538°C (1000°F)

Control Valve Pressure-Temperature Chart for Standard Class ASTM A351 Grade CF3 Cast Steel In Accordance with ASME B16.34-2013

Temperature	Class 150	Class 300	Class 600	Class 900	Class 1500
°C	Bar
-29 to 38	19.0	49.6	99.3	148.9	248.2
50	18.3	47.8	95.6	143.5	239.1
100	15.7	40.9	81.7	122.6	204.3
150	14.2	37.0	74.0	111.0	185.0
200	13.2	34.5	69.0	103.4	172.4
250	12.1	32.5	65.0	97.5	162.4
325	9.3	30.2	60.4	90.7	151.1
350	8.4	29.6	59.3	88.9	148.1
375	7.4	29.0	58.1	87.1	145.2
400	6.5	28.4	56.9	85.3	142.2
425	5.5	28.0	56.0	84.0	140.0
°F	psig
-20 to 100	275	720	1,440	2,160	3,600
200	230	600	1,200	1,800	3,000
300	205	540	1,075	1,615	2,690
400	190	495	995	1,490	2,485
500	170	465	930	1,395	2,330
600	140	440	885	1,325	2,210
650	125	430	865	1,295	2,160
700	110	420	845	1,265	2,110
750	95	415	825	1,240	2,065
800	80	405	810	1,215	2,030

Control Valve Pressure-Temperature Chart for Standard Class ASTM A351 Grades CF8M and CG8M(1) Cast Steel In Accordance with ASME B16.34-2013

Temperature	Class 150	Class 300	Class 600	Class 900	Class 1500
°C	Bar
-29 to 38	19.0	49.6	99.3	148.9	248.2
50	18.4	48.1	96.2	144.3	240.6
100	16.2	42.2	84.4	126.6	211.0
150	14.8	38.5	77.0	115.5	192.5
200	13.7	35.7	71.3	107.0	178.3
250	12.1	33.4	66.8	100.1	166.9
300	10.2	31.6	63.2	94.9	158.1
325	9.3	30.9	61.8	92.7	154.4
350	8.4	30.3	60.7	91.0	151.6
375	7.4	29.9	59.8	89.6	149.4
400	6.5	29.4	58.9	88.3	147.2
425	5.5	29.1	58.3	87.4	145.7
450	4.6	28.8	57.7	86.5	144.2
475	3.7	28.7	57.3	86.0	143.4
500	2.8	28.2	56.5	84.7	140.9
538	1.4	25.2	50.0	75.2	125.5
550	1.4(2)	25.0	49.8	74.8	124.9
575	1.4(2)	24.0	47.9	71.8	119.7
600	1.4(2)	19.9	39.8	59.7	99.5
625	1.4(2)	15.8	31.6	47.4	79.1
650	1.4(2)	12.7	25.3	38.0	63.3
675	1.4(2)	10.3	20.6	31.0	51.6
700	1.4(2)	8.4	16.8	25.1	41.9
725	1.4(2)	7.0	14.0	21.0	34.9
750	1.4(2)	5.9	11.7	17.6	29.3
775	1.4(2)	4.6	9.0	13.7	22.8
800	1.2(2)	3.5	7.0	10.5	17.4
816	1.0(2)	2.8	5.9	8.6	14.1

Temperature	Class 150	Class 300	Class 600	Class 900	Class 1500
°C	Bar
-20 to 100	275	720	1,440	2,160	3,600
200	235	620	1,240	1,860	3,095
300	215	560	1,120	1,680	2,795
400	195	515	1,025	1,540	2,570
500	170	480	955	1,435	2,390
600	140	450	900	1,355	2,255
650	125	440	885	1,325	2,210
700	110	435	870	1,305	2,170
750	95	425	855	1,280	2,135
800	80	420	845	1,265	2,110
850	65	420	835	1,255	2,090
900	50	415	830	1,245	2,075
950	35	385	775	1,160	1,930
1000	20	365	725	1,090	1,820
1050	20	360	720	1,080	1,800
1100	20(2)	305	610	915	1,525
1150	20(2)	235	475	710	1,185
1200	20(2)	185	370	555	925
1250	20(2)	145	295	440	735
1300	20(2)	115	235	350	585
1350	20(2)	95	190	290	480
1400	20(2)	75	150	225	380
1450	20(2)	60	115	175	290
1500	15(2)	40	85	125	205

1. CG8M is limited to 538°C   (1000°F).
2. Flanged end ratings terminate at 538°C (1000°F) for CF8M.

Pressure Control Valve Characteristic

The flow characteristic of the control valve is the relationship between valve travel from 0% to 100% corresponding to the flow Cv/Kv value.

1. EQ% Characteristic (Equal Percentage Characteristic)

The ratio of the change in flow rate to the change in valve opening position is proportional to the flow rate before the change and is expressed by the following equation.

dCv/dL = KCv,

so Cv = e^K(L-1)

2. Linear % Characteristic (Linear Characteristic)

With the linear characteristic, the valve opening position and the flow rate are proportional to each other.

Cv = KL

L is the valve opening position, and K is a constant.

3. Quick Opening Characteristic

The quick opening characteristic is a kind of on-off flow characteristic, an efficient characteristic that can be used to switch the flow rate between maximum and minimum.

The inherent flow characteristic of the control valve is the relationship between the flow and travel of the valve to a constant pressure drop across the valve.

Why do different control valves have different characteristics?

What is valve gain?

What is Cavitation for control valves?

The valve gain is the increased flow rate generated by an increasing change in plug position. This gain is a function of valve size and type, plug configuration, and system operating conditions. The gain at any point in the valve travel is equal to the slope of the valve flow characteristic curve at that point.

What are the Cv value and Kv value for the control valve?

The valve coefficient Cv is the number of US gallons per minute of water at 60 °F that will flow through a valve at a specific opening with a 1 psi pressure drop across the control valve. The flow factor Kv Flowrate in m³/h of water at between 25 °C will create a pressure drop of one bar across the control valve. 

What is CV of Control Valves?