32:
20:
163:. The more uniform is obtained supersaturation, the sharper is particle minimal size cutoff. During the heterogeneous nucleation process in the nucleation chamber, particles grow up to 10âĶ12 Ξm large and so are conveniently detected by usual techniques, such as laser nephelometry (measurement of light pulses scattered by the grown-up particles).
158:
where nucleation occur. Temperature difference between the heater and the cooler determines the supersaturation, which in its turn determines the minimal size of particles that will be detected (the greater the difference, the smaller particles get counted). As proper nucleation conditions occur in
153:
On the right, a diffusional thermal cooling CPC is shown in operation. In order to ensure a high vapour content, the working liquid is in contact with a hollow block of porous material that is heated. Then the humified air enters the
27:. Notation: 1 â air inlet; 2 â porous material block, which is heated to saturator temperature, 3 â working fluid in reservoir, 4 â condenser, 5 â focusing nozzle, 6 â laser-based counter, 7 â air pump, 8 â air exhaust.
137:
supersaturation criteria. This amount grows (vapor pressure decreases) along with decrease in particle size, the critical diameter for which condensation can occur at the present saturation level is called
35:
Equipment used for area sampling of airborne nanomaterials. The instruments shown here include a condensation particle counter, aerosol photometer, and two air sampling pumps for filter-based analysis.
159:
the center of the flow, sometimes incoming flow is divided: most of it undergoes filtering and forms the sheath flow, which the rest of flow, still containing particles, is inserted into via a
121:
nucleation (droplet growth on surface of a suspended solid particle) can occur at supersaturation as small as 1%. The greater vapour content is needed because, according to
263:
186:
150:â stable enough to ensure further growth is possible), which will produce false counts. This usually starts at ca. 300% supersaturation.
109:
and larger. This is of special importance because particles sized down from 50 nm are generally undetectable with conventional
23:
The schematic of a condensation particle counter, operated by diffusional thermal cooling. Drawn according to the description at
219:
Aerosol
Measurement: Principles, Techniques, and Applications, edited by Pramod Kulkarni, Paul A. Baron, Klaus Willeke, p384,
220:
268:
288:
273:
74:
55:
particles by first enlarging them by using the particles as nucleation centers to create droplets in a
245:
24:
283:
31:
133:
surface is less than over a plane, thus greater content of vapor in air is required to meet
181:"General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories"
110:
8:
70:
56:
278:
147:
191:
105:
Condensation particle counters are able to detect particles with dimensions from 2
48:
126:
122:
114:
91:
80:
257:
196:
118:
180:
143:
130:
63:
142:. The supersaturation level must, however, be small enough to prevent
160:
117:
is ca. 100âĶ200 % in condensation chamber, despite the fact that
106:
95:
90:
The most usually used (also the most efficient) method is cooling by
73:
using an expansion chamber. This was the original technique used by
146:
nucleation (when liquid molecules collide so often that they form
52:
25:
http://www.cas.manchester.ac.uk/restools/instruments/aerosol/cpc/
155:
99:
19:
187:
National
Institute for Occupational Safety and Health
255:
264:Meteorological instrumentation and equipment
241:
239:
237:
62:Three techniques have been used to produce
234:
195:
94:. Most abundantly used working fluid is
30:
18:
256:
215:
213:
246:Condensation Particle Counters (CPC)
231:Kulkarni, Baronand and Willeke, p381
13:
210:
14:
300:
102:is also encountered in this use.
225:
173:
1:
166:
86:Mixing of hot and cold gases.
41:condensation particle counter
7:
10:
305:
197:10.26616/NIOSHPUB2012147
113:techniques. Usually the
51:that detects and counts
16:Type of particle counter
36:
28:
222:retrieved 15 May 2012
34:
22:
269:Counting instruments
98:; during last years
289:Aerosol measurement
190:: 29â30. May 2012.
71:Adiabatic expansion
274:Particle detectors
57:supersaturated gas
37:
29:
92:thermal diffusion
81:Thermal diffusion
296:
248:
243:
232:
229:
223:
217:
208:
207:
205:
204:
199:
177:
49:particle counter
304:
303:
299:
298:
297:
295:
294:
293:
254:
253:
252:
251:
244:
235:
230:
226:
218:
211:
202:
200:
179:
178:
174:
169:
140:Kelvin diameter
127:vapour pressure
123:surface science
115:supersaturation
17:
12:
11:
5:
302:
292:
291:
286:
281:
276:
271:
266:
250:
249:
233:
224:
209:
171:
170:
168:
165:
88:
87:
84:
78:
15:
9:
6:
4:
3:
2:
301:
290:
287:
285:
284:Air pollution
282:
280:
277:
275:
272:
270:
267:
265:
262:
261:
259:
247:
242:
240:
238:
228:
221:
216:
214:
198:
193:
189:
188:
182:
176:
172:
164:
162:
157:
151:
149:
145:
141:
136:
132:
128:
124:
120:
119:heterogeneous
116:
112:
108:
103:
101:
97:
93:
85:
82:
79:
76:
72:
69:
68:
67:
65:
60:
58:
54:
50:
46:
42:
33:
26:
21:
227:
201:. Retrieved
184:
175:
152:
139:
134:
104:
89:
61:
44:
40:
38:
144:homogeneous
75:John Aitken
258:Categories
203:2017-03-05
167:References
125:laws, the
64:nucleation
161:capillary
96:n-butanol
279:Aerosols
148:clusters
77:in 1888.
129:over a
111:optical
53:aerosol
156:cooler
135:actual
131:convex
185:U.S.
100:water
47:is a
192:doi
45:CPC
43:or
260::
236:^
212:^
183:.
107:nm
66::
59:.
39:A
206:.
194::
83:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
