How to Calculate "Spray Angle" and "Spray Coverage Area"?

Bobby Brown

Post 2016-12-14

1. What is "Spray Angle"?
2. How to Calculate the Spray Angle?
3. How to Calculate the Theoretical Spray Coverage Area?
4. Spray Angle and Coverage Area Reference Table
- Unit: inch
- Unit: mm
5. About Angles and Coverage Areas
4. 3 Key Distance Decisions for Choosing Nozzle Angles

1. What is "Spray Angle"?

| llustration of the Spray Coverage Area of the Nozzle

When we refer to the spray angle (spray cone angle), we are talking about the angle formed between the centerline of the nozzle outlet and the edges of the spray on both sides. After the liquid exits the nozzle, it cannot continue in a tangential direction due to the effects of gravitational acceleration and air resistance. As a result, the the "actual spray coverage" may be smaller than the "theoretical spray coverage"

2. How to Calculate the Spray Angle?

Currently, there is no internationally standardized method for measuring spray angles, but common measurement techniques include protractor-based measurement and optical measurement.

Traditional Protractor Measurement Method:
The nozzle is fixed and kept in a horizontal position. A protractor is used to align with the edges of the spray emitted from the nozzle center, and the spray angle is read. This method is low-cost but may be affected by human error.
Optical Measurement Method:
Using a stable light source, a high-resolution camera captures the shape of the spray. Specialized computer software, such as CAD or image processing software, is then used to calculate the spray angle. This method is highly accurate but requires expensive software and professional expertise. LORRIC employs the optical measurement method to ensure the quality of every nozzle before shipment.

3. How to Calculate the Theoretical Spray Coverage Area?

The spray angle is influenced by both the size of the nozzle’s spray orifice and the distance between the nozzle and the target surface. This relationship also determines the spray coverage area and the density of the liquid relative to the covered area.

| Theoretical spray coverage of nozzles

To calculate the theoretical spray coverage area, we need to know both the spray angle and the distance between the nozzle outlet and the object. The formula for calculating the spray coverage area is as follows:
Theoretical Spray Coverage =2⋅Distance⋅tan(Spray Angle/2)

| Calculate the theoretical spray coverage of nozzles

In summary, the relationship between angle, coverage area, and distance is: generally, the larger the spray angle, the wider the coverage area, but the spray distance will be relatively shorter. Conversely, a smaller spray angle results in a narrower coverage area but allows the spray to reach farther distances.

4. Spray Angle and Coverage Area Reference Table

LORRIC provides a reference table showing the calculated spray angles and corresponding coverage areas based on the formula. It is important to note that due to factors like gravity and aerodynamic drift, the spray angle can only be maintained over a limited distance—typically up to 300 mm from the nozzle outlet.

Unit: inch

Spray Angle (°)		Theoretical Spray Coverage (Unit：inch)
Spray Angle (°)		40	55	60	65	70	75	80	90	100	120	170
Distance (inch)	1.0	0.7	1.0	1.2	1.3	1.4	1.5	1.7	2.0	2.4	3.5	23
	1.5	1.1	1.6	1.7	1.9	2.1	2.3	2.5	3.0	3.6	5.2	34
	2.0	1.5	2.1	2.3	2.5	2.5	2.8	4.2	4.0	6.0	8.7	57
	2.5	1.8	2.6	2.9	3.2	3.5	3.8	5.0	5.0	7.2	10	69
	3.0	2.2	3.1	3.5	3.8	4.2	4.6	5.0	6.0	7.2	10	69
	3.5	2.5	3.6	4.0	4.5	4.9	5.4	5.9	7.0	8.3	12	80
	4.0	2.9	4.2	4.6	5.1	5.6	6	6.7	8.0	10	14	91
	4.5	3.3	4.7	5.2	5.7	6.3	7	7.6	9.0	11	16	103
	5	3.6	5.2	5.8	6.4	7	8	8.4	10	12	17	114
	6	4.4	6.2	6.9	7.6	8	9	10	12	14	21	137
	7	5.1	7.3	8.1	8.9	10	11	12	14	17	24	160
	8	5.8	8.3	9	10	11	12	13	16	19	28	183
	9	6.6	9.4	10	11	13	14	15	18	21	31	206
	10	7.3	10.4	12	13	14	15	17	20	24	35	229
	11	8.0	11.5	13	14	15	17	18	22	26	38	251
	12	8.7	12.5	14	15	17	18	20	24	29	42	274
	13	9.5	12	15	18	20	22	23	26	31	45	297
	14	10	13	16	17.8	19.7	21.8	24	28	33	48	320
	18	13	19	21	23	25	28	30	32	43	62	411
	20	15	21	23	25	28	31	34	36	48	69	457
	22	16	23	25	28	31	34	37	40	52	76	503
	24	17	25	28	31	34	37	40	44	57	83	549
	26	19	27	30	33	36	40	44	48	62	90	594
	28	20	29	32	36	39	43	47	52	67	97	640
	30	22	31	35	38	42	46	50	56	72	104	686
	32	23	33	37	41	45	49	54	60	76	111	732
	34	25	35	39	43	48	52	57	64	81	118	777
	36	26	37	42	46	50	55	60	60	86	125	823

Unit: mm

Spray Angle (°)		Theoretical Spray Coverage (Unit：mm)
Spray Angle (°)		55	60	65	70	80	75	90	100	120
Distance (mm)	30	31	35	38	42	50	46	60	72	104
	40	42	46	51	56	67	61	80	95	139
	50	52	58	64	70	84	77	100	119	173
	60	62	69	76	84	101	92	120	143	208
	70	73	81	89	98	117	107	140	167	242
	80	83	92	102	112	160	123	160	191	277
	90	94	104	115	126	180	138	180	215	312
	100	104	115	127	140	200	153	200	238	346
	110	115	127	140	154	220	169	220	262	381
	120	125	139	153	168	240	184	240	286	416
	130	135	150	166	182	260	200	260	310	450
	140	146	162	178	196	280	215	280	334	485
	150	156	173	191	210	300	230	300	358	520
	200	208	231	255	280	400	307	400	477	693
	250	260	289	319	350	500	384	500	596	866
	300	312	346	382	420	600	460	600	715	1039
	350	364	404	446	490	700	537	700	834	1212
	400	416	462	510	560	800	614	800	953	1386
	450	469	520	573	630	900	691	900	1073	1559
	500	521	577	637	700	1000	767	1000	1192	1732
	550	573	635	701	770	1100	844	1100	1311	1905
	600	625	693	764	840	1200	921	1200	1430	2078
	650	677	751	828	910	1300	998	1300	1549	2252
	700	729	808	892	980	1400	1074	1400	1668	2425
	750	781	866	956	1050	1500	1151	1500	1788	2598
	800	833	924	1019	1120	1600	1228	1600	1907	2771
	850	885	981	1083	1190	1700	1304	1700	2026	2944
	900	937	1039	1147	1260	1800	1381	1800	2145	3118
	950	989	1097	1210	1330	1900	1458	1900	2264	3291
	1000	1041	1155	1274	1400	2000	1535	2000	2384	3464

5. About Angles and Coverage Areas

| About Angles and Coverage Areas

At a distance of 300 mm, theoretical spray area:

90° angle: 60cm, 0.28㎡ per unit
170° angle: 150cm, 1.76㎡ per unit (approximately 6.3 times)

4. 3 Key Distance Decisions for Choosing Nozzle Angles

1 ) Distance to Target

The distance between the nozzles and the target area, such as a plant canopy, significantly affects spray deposition. Optimal distance settings ensure efficient coverage while minimizing drift and wastage. Adjustments should consider the type of spray and the specific application requirements to maximize efficacy.

| Schematic diagram of Distance to Target

2 ) Distance Between Adjacent Nozzles

Maintaining the right distance between adjacent nozzles is crucial for achieving uniform coverage across the target area. Incorrect spacing can lead to overlapping spray zones or missed areas, affecting the overall effectiveness of the application. This distance varies depending on the nozzle type and the desired coverage pattern.

3 ) Distance Between Spray Bars

For non-fan nozzles, such as solid cone, hollow cone, and spiral nozzles, the distance between spray bars plays a critical role in angle selection and, consequently, in the coverage pattern and effectiveness of the spray. Proper adjustment ensures optimal spray overlap and uniform distribution across the target.